JP2000169872A - Grease for high-speed roller bearing and roller bearing for spindle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grease for high-speed roller bearings with reduced vibration in which the grease or its base oil in the roller bearings is not separated or not splashed out of the bearings by the centrifugal force on the high speed rotation, as the rotation torque of the bearing is lowered, and provide the roller bearing for the spindle having a long duration time and sufficiently increase the built-in pre-pressure between a main shaft and an inner ring, when the main shaft is mounted. SOLUTION: This grease for high-speed roller bearings is prepared by adding an aliphatic urea thickener, for example, diurea or polyurea to a base oil with a dynamic viscosity of 30-60 cSt at 40 deg.C so that the worked penetration of the grease may become 230-280 according to JIS K2220 5.3 and the oil separation may become 1-10 wt.%, when the centrifugal force of 2,500G is loaded to the grease for 4.5 hours. This grease is enclosed in a roller bearing and the bearing is used as a roller bearing for a spindle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease for a high-speed rolling bearing and a rolling bearing for a spindle used in a rolling bearing for supporting a high-speed rotating shaft such as a machine tool spindle (spindle).

[0002]

2. Description of the Related Art A main shaft of a machine tool preferably rotates at a high speed in order to increase machining efficiency, and various lubrication techniques are applied to its bearing.

[0003] As a lubrication method suitable for a spindle rotating at a high speed, for example, methods such as oil mist lubrication, air-oil lubrication, and jet lubrication are known.

However, such a lubrication method requires auxiliary equipment such as compressed air and a lubricating device, and is one of the causes for increasing the initial cost and running cost of a machine tool. It can be said that lubrication is a preferable lubrication method requiring less maintenance.

For example, high-speed rolling bearings that support a rotating shaft that rotates at a high speed of 2000 to 8000 rpm or more include angular ball bearings and cylindrical roller bearings that support a machine tool main spindle (spindle) and the like.

As shown in FIG. 6 (a), an angular contact ball bearing is capable of applying an axial load from one direction in addition to a radial load, and is capable of contacting a steel ball 1 with an inner ring 2 and an outer ring 3. A straight line connecting the points has an angle (contact angle) with respect to the radial direction.

[0007] As a lubricant used for high-speed rolling bearings such as angular ball bearings and cylindrical roller bearings, lubrication grease is used which does not require maintenance such as lubrication and which is adjusted to a degree that does not pollute the surrounding environment. Is preferred. Such lubricating grease is required to have a long service life, a low temperature rise when a rolling bearing is used, and low vibration.

[0008] As a type of grease used for a rolling bearing for a spindle, there is a low-viscosity ester grease added with barium soap and the like, and as a commercially available product, Stabrags NBU15 manufactured by Kleuba is known. .

Incidentally, regarding the lubrication means suitable for the rolling bearing for the spindle, the DN value (shaft diameter D: mm × rotation speed N:
The corresponding relationship with (rpm) will be described below.

(A) a dn value of a spindle rolling bearing suitable for grease lubrication = about 800,000 or less; (b) a dn value of a spindle rolling bearing suitable for oil mist or air-oil lubrication = about 800,000 to 1.5 million; (c) dn value of spindle rolling bearing suitable for jet lubrication = 1.5 million or more,

[0011]

The lubricating characteristics and problems required for grease for a high-speed rolling bearing such as a rolling bearing for a spindle are summarized below.

(A) Long life In order to extend the lubrication life of a rolling bearing as much as possible, as described in the following (i) to (iii), a lubricant (grease or its base) is removed from the rolling bearing. It is necessary that oil (oil) does not leak easily, heat resistance is good, and an oil film thickness necessary for lubrication is formed.

(I) Prevention of Leakage of Lubricant from Bearing When grease-lubricated rolling bearings are operated at high speed, the grease in the rolling bearings flows out of the bearings due to centrifugal force, or the base oil in the grease is discharged. Separation and outflow, it is difficult to stay near the transfer surface that greatly contributes to lubrication,
Prone to poor lubrication.

In order to prevent such a situation, a sealing device such as a seal or a shield plate is mounted on the rolling bearing. However, depending on the structure of the bearing, it may not be possible to mount the sealing device. However, there are cases where the lubricant or lubricating oil cannot be completely sealed.

The applicant of the present invention forms a circumferential groove-shaped grease reservoir 5 on the inner surface of the outer ring 4 of the angular ball bearing as shown in FIG. 6B to physically prevent grease leakage. Angular ball bearings have been proposed (reference numeral 6 in FIG. 6).
Denotes an inner ring, and 7 denotes a retainer. ) This is an improvement that does not depend on the physical properties of the grease.

(Ii) Heat resistance (durability) of lubricant When the speed of the bearing is increased, the rolling surface of the bearing locally generates heat to a high temperature. At this time, the grease having poor heat resistance is thermally degraded, and the life of the grease is reduced. Shrinks significantly.

To solve such problems, attempts have been made to use heat-resistant thickeners and base oils or to add antioxidants. However, these attempts have not led to a sufficient improvement in durability.

(Iii) Improvement of lubricity (oil film thickness) In the existing grease, when the base oil viscosity is increased, the shear friction resistance increases, the rotational torque increases, and the calorific value increases. Therefore, the base oil viscosity is kept low. For this reason, the oil film of the lubricating oil, which has become low in viscosity due to the temperature rise accompanying the high speed, sometimes becomes thin and causes sliding wear.

(B) Low torque properties (suppression of temperature rise) Existing greases for high-speed bearings have a low base oil viscosity as described above. However, when the bearing rotates at high speed, the temperature rises. The viscosity is remarkably reduced, and an oil film having a thickness required for lubrication cannot be formed.

(C) Low Vibration Grease may increase bearing vibration depending on the type of thickener. That is, the vibration of the rolling bearing lubricated with the grease containing the thickener that forms a large and hard aggregate becomes large. Incidentally, since soap-based thickeners are generally soft, there are few factors that increase the vibration of bearings. Therefore, greases using soap-based thickeners have been used as greases for high-speed rolling bearings. Also, when the oil film is broken, the vibration of the rolling bearing increases.

As described above, when the conventional grease is used for a high-speed rolling bearing, there is a problem that required physical properties such as long life of the bearing, low torque and low vibration cannot be satisfied.

In recent years, the use of rolling bearings has become increasingly severe, and the number of spindle rolling bearings used at high speeds, such as DN values of 800,000 or more and 1,000,000 or more, has been increasing. With such an increase in the rotational speed of the bearing, it is extremely difficult to satisfy all the performances required for the bearing with existing grease.

Accordingly, an object of the invention relating to the grease for a high-speed rolling bearing of the present invention is to solve the above-mentioned problems and to prevent the base oil of grease in the rolling bearing from being separated by centrifugal force during high-speed rotation, or An object of the present invention is to provide grease for high-speed rolling bearings in which lubricating oil (base oil) does not scatter outside the bearing, reduces the rotational torque of the bearing during high-speed rotation, and suppresses vibration of the bearing.

Generally, a temperature difference occurs between the inner and outer rings,
That is, the inner ring side is expanded at a higher temperature than the outer ring side, and the clearance inside the bearing is reduced.

As described above, in the conventional rolling bearing for a spindle, the gap inside the bearing is reduced during rotation at high speed.
It is necessary to set the built-in preload (initial preload) at the time of attaching the main shaft to a small value in advance by assuming a reduced amount of the gap, and there is also a problem that the fixing force (rigidity) between the main shaft and the bearing is reduced accordingly.

Accordingly, an object of the invention relating to a rolling bearing for a spindle according to the present invention is to solve the above-mentioned problems, exhibit excellent rotational characteristics of low torque and low vibration during high-speed rotation, and have a long service life. A long-term (long-life) rolling bearing for a spindle, and a spindle rolling bearing that can be mounted so that the built-in preload (initial preload) can be sufficiently increased to obtain high rigidity when a main shaft is mounted.

[0027]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, in the invention relating to the grease for a high-speed rolling bearing of the present invention,
The grease for high-speed rolling bearings is a grease obtained by mixing an aliphatic urea-based thickener with a base oil having a kinematic viscosity at 40 ° C of 30 to 60 cSt. The grease for a high-speed rolling bearing is prepared by adjusting the amount of the aliphatic urea-based thickener to the mixing consistency of the grease (JIS K2220 5.
It is preferable that 3) is a compounding amount of 230 to 280.

Alternatively, the grease for high-speed rolling bearings may have an oil separation rate of 1 to 10% by weight when the grease is loaded with a centrifugal force of 2500 G for 4.5 hours. It is preferable to set the blending amount.

The grease for a high-speed rolling bearing according to the present invention configured as described above sets the viscosity (kinematic viscosity) of the base oil in a relatively high predetermined range and employs a specific type of thickener. However, the present invention is limited to applications of high-speed rolling bearings, and in such a state of use of the bearing, the shear resistance (rotation torque) does not increase.

In the grease for a high-speed rolling bearing according to the present invention, the viscosity (kinematic viscosity) of the base oil is set to a relatively high predetermined range, so that the grease adheres to a friction surface which slides at a high speed. It has good properties and forms an oil film with the required thickness for lubrication.

The amount of the aliphatic urea-based thickener is adjusted according to the mixing consistency of grease (JIS K2220 5.3).
Is set to 230 to 280, and a predetermined oil separation rate is obtained even when a predetermined strength of centrifugal force is applied for a predetermined time. Therefore, when the rolling bearing rotates at high speed, the grease is used as the base oil and the thickener. The lubricating oil is not excessively separated, and an amount of lubricating oil necessary for lubricating the bearing is supplied to the friction surface, so that the lubricating oil (base oil) does not scatter or leak outside the bearing.

Since the aliphatic urea thickener is a thickener having high heat resistance, the grease is a highly durable high-speed rolling bearing grease without thermal deterioration. Furthermore, since the aliphatic urea-based thickener is a relatively soft thickener, it does not vibrate the rolling bearing that rotates at high speed.

As described above, the grease for a high-speed rolling bearing according to the present invention has excellent physical properties, and has a DN value (shaft diameter D: mm × rotation speed N: rpm) of 800,000 or more, preferably 100,000 or more. A grease that satisfies all the required performances of high-performance high-speed rolling bearings used at high speeds of 10,000 or more.

Further, in order to solve the above-mentioned problem, in the invention relating to the rolling bearing for a spindle of the present invention, the temperature of 40 ° C.
A grease is prepared by blending an aliphatic urea thickener with a base oil having a kinematic viscosity of 30 to 60 cSt at 230 to 280 so that the mixing consistency (JIS K2220 5.3) becomes 230 to 280, and the grease is used as a rolling bearing. The rolling bearing for the spindle is sealed in the bearing. As this spindle rolling bearing, a spindle rolling bearing composed of an angular ball bearing or a cylindrical roller bearing can be adopted.

Since the spindle rolling bearing of the present invention configured as described above uses grease for a high-speed rolling bearing having the above-described excellent characteristics, the viscosity of the base oil of the grease (dynamic Viscosity) and low resistance when subjected to shearing force at high temperature and high speed.

Further, in the rolling bearing for a spindle according to the present invention, the grease does not flow out of the bearing in a state where a high centrifugal force is applied, and the separation speed of the base oil in the grease is appropriate, so that it is necessary for bearing lubrication. The oil amount is supplied stably for a long period of time, and an oil film having a thickness required for lubrication is formed on the raceway surface which slides at a high speed.

Since the grease held in the bearing of the spindle rolling bearing does not deteriorate due to heat, it becomes a bearing exhibiting excellent rotation characteristics such as low torque and low vibration, and has good use durability (long life). Long) rolling bearing for spindles.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION In the invention according to each claim of the present application, it is preferable to use a lubricating oil having good heat resistance as a base oil having a kinematic viscosity at 40 ° C. of 30 to 60 cSt. A well-known lubricating oil having a predetermined kinematic viscosity can be employed without any particular limitation. Preferred lubricating oils include synthetic hydrocarbon oils or polyol ester oils or mixtures thereof. These are preferable in that they have excellent heat resistance as compared with diester base oils.

The base oil having the predetermined kinematic viscosity has a small consistency (mixing consistency), that is, has a good adhesion to a metal surface, but has a large viscous resistance in a bearing, and has a large rotational torque and frictional heat. It is thought that this will cause an increase. However, by combining and combining the base oil having the predetermined kinematic viscosity and the aliphatic urea-based thickener, the shear resistance at the time of kneading the grease can be reduced.

That is, the grease according to the present invention is a grease having improved adhesion and improved separation resistance of the base oil by blending the above-mentioned combination.
Rolling bearings using this have excellent adhesion and separation resistance to friction surfaces even when used at a high DN value (shaft diameter D: mm x rotation speed N: rpm) of 800,000 or more or 1,000,000 or more. It is a thing.

The aliphatic urea thickener used in the invention according to each claim of the present application is composed of an aliphatic urea compound, which is a diurea having two or more urea bonds -NHCONH- in the molecular structure. Or polyurea. An aliphatic urea compound is a compound in which an aliphatic hydrocarbon group (methylene group) is bound by a urea bond as described above. Further, polyurea is a polymer compound having a linear structure having a urea bond -NHCONH- in a repeating unit of a main chain. For example,-[-RNHCONH
-] N- or-[-RNHCONHR'NHCON
H-] n- (where R and R 'are methylene groups).

Such an aliphatic urea thickener has a linear structure similar to that of a soap thickener and does not contain a rigid molecule such as alicyclic or aromatic, so that it is flexible. There is almost no effect on the sound of the bearing. Although the heat resistance as a compound is slightly inferior to that of an alicyclic or aromatic urea compound, it has sufficient heat resistance corresponding to the object of the present invention.

The reason why no alicyclic or aromatic urea compound is used as the thickener is that the aggregates of these thickeners are large and hard, and adversely affect the acoustic properties due to the vibration of the bearing. It is. In order to improve such a thickener, a method may be employed in which the above aggregates are refined by rolling or milling during the grease manufacturing process, but this method is to sufficiently suppress the vibration of the bearing. And the cost increases due to the increase in the number of manufacturing steps.

The amount of the aliphatic urea-based thickener is adjusted according to the grease mixing consistency (JIS K2220 5.
The reason why 3) is set to 230 to 280 is that when a centrifugal force of 2500 G is applied for 4.5 hours, the oil separation rate of the base oil is 1 to 1
If the separability of the base oil is reduced below a predetermined range, lubricating oil required for lubricating the bearing is not supplied from the grease, and the lubricating life is undesirably reduced. Conversely, if the separation rate of the base oil exceeds the above-mentioned predetermined range, the lubricating oil scatters or leaks out of the bearing when the above-mentioned predetermined centrifugal force is applied, which is not preferable.

[0045]

EXAMPLES AND COMPARATIVE EXAMPLES [Example 1] A mixed oil of a synthetic hydrocarbon type and a polyol ester having a kinematic viscosity of 40 cSt at 40 ° C. was used as a thickener with an aliphatic urea as a base oil and mixed at room temperature. A grease having a consistency of 243 (25 ° C., 60 times mixing consistency, JIS K2220 5.3) was prepared. Using this grease, the following A
To C were evaluated.

<A. Temperature Rise, Vibration, and Durability> 4.8 ml of test grease was uniformly filled in the inner space of the bearing in an angular ball bearing having an inner ring inner diameter of 100 mm, an outer ring outer diameter of 150 mm, and a width of 24 mm. This bearing is 200
After running-in at 0, 4000, 6000, and 8000 rpm for 1 hour each, and then at 10000 rpm for 5 hours, the temperature rise (° C.) of the outer diameter surface of the bearing outer ring at each rotation speed.
And the vibration (G) of the bearing was measured, and these results are shown in the table of FIG.

The durability was evaluated by using the above-described angular ball bearings of the same dimensions, performing a break-in operation under the same conditions as described above, then increasing the rotation speed to 13000 rpm, performing a continuous operation, and examining the life time (hour). . The life was determined when the vibration value exceeded 1 G, and was checked up to 1000 hours.
The results are shown in the chart of FIG.

<B. Oil Retention (Oil Separation Rate)> Using a centrifuge, 5 g of test grease was placed in a centrifuge tube, and
An acceleration of 500 G was applied for 4.5 hours. On the way, 1
At each time, the base oil that emerged on the surface of the test grease was separated and its weight was measured.

The cumulative separation amount at each measurement time was divided by the initial sample amount, and the result was multiplied by 100 to obtain the separation rate (% by weight) at each time. The results are shown in the table of FIG.

<C. Adhesion Property> The test apparatus shown in FIG. 4 has a main shaft 8 rotatable at a predetermined speed by a drive motor (not shown).
A bowl-shaped jig 9 is fixed and a bearing steel ring 1 is
The test grease 11 is applied to the inner peripheral surface thereof at a fixed thickness, and the main shaft 8 is rotated on the assumption that a rolling bearing is used to check the adhesion of the test grease.

To this test apparatus, 3.5 g of test grease was applied to predetermined positions so as to have a uniform thickness, and the main shaft 8 was rotated at 8000 rpm to apply 20 g to the test grease.
A 43 G acceleration was applied for one hour. Thereafter, the residual amount (weight) of the test grease was measured to evaluate the adhesion rate (residual weight%). The results are shown in the chart of FIG.

The test results of the above A to C are as follows:
Very good, に: good, Δ: inferior, ×: very poor, and evaluated in four stages.

[0053]

[Table 1]

Example 2 As a thickener, aliphatic urea,
Grease having a consistency of 260 was prepared by using a synthetic hydrocarbon oil having a kinematic viscosity of 42.7 cSt at 40 ° C. as a base oil. Tests A to C were performed on the grease under the same conditions as in Example 1 to evaluate the performance, and the results are shown in FIGS.

[Example 3] Aliphatic urea,
A base oil is a mixed oil of a synthetic hydrocarbon oil having a kinematic viscosity of 47 cSt at 40 ° C. and a polyol ester oil.
54 greases were prepared. Tests A to C were performed on the grease under the same conditions as in Example 1 to evaluate the performance, and the results are shown in FIGS.

[Example 4] As a thickener, aliphatic urea,
A grease having a consistency of 266 was prepared using a polyol ester oil having a kinematic viscosity of 32 cSt at 40 ° C. as a base oil. Tests A to C were performed on the grease under the same conditions as in Example 1 to evaluate the performance, and the results are shown in FIGS.

[Comparative Example 1] A grease having a consistency of 267 using a thickening agent as an alicyclic urea compound, and using a mixed oil of a synthetic hydrocarbon oil having a kinematic viscosity of 58 cSt at 40 ° C and a dialkyldiphenyl ether oil as a base oil. Was prepared. Tests A to C were performed on the grease under the same conditions as in Example 1 to evaluate the performance, and the results are shown in FIGS.

Comparative Example 2 The thickener was an aromatic urea,
A grease having a consistency of 300 was prepared by using a dialkyldiphenyl ether-based lubricating oil of 72 cSt at 40 ° C. as a base oil. Tests A to C were performed on the grease under the same conditions as in Example 1 to evaluate the performance.
3, 5 and Table 1.

[Comparative Example 3] A thickener was a lithium complex, a mixed oil of a synthetic hydrocarbon-based lubricating oil and a diester-based lubricating oil having a kinematic viscosity of 22 cSt at 40 ° C was used as the base oil, and grease having a consistency of 300 was used. Prepared. Tests A to C were performed on the grease under the same conditions as in Example 1 to evaluate the performance, and the results are shown in FIGS.

[Comparative Example 4] The thickener was lithium complex, and the base oil was a mixed oil of mineral oil and diester oil at 40 ° C.
A grease having a consistency of 280 was prepared using a kinematic viscosity of 20 cSt. Tests A to C were performed on the grease under the same conditions as in Example 1 to evaluate the performance, and the results were shown in FIGS.
5 and Table 1.

As is clear from the results shown in FIGS. 1 to 3 and 5 and Table 1, Comparative Example 1 did not have a very poor oil separation rate and adhesion, but had a large bearing vibration and a short life. Was.
Comparative Example 2 showed an appropriate value for the oil separation rate,
The temperature rise and vibration of the bearing were large, and the life was shortened in a short time. In Comparative Example 3, although the adhesion rate and the temperature rise of the bearing were not so bad, the oil separation rate was large, the vibration value was high when the bearing was operated, and the life was as long as the existing grease (50 hours). In Comparative Example 4, the vibration value and temperature rise of the bearing were good.
The adhesion was poor and the life of the bearing was short.

On the other hand, the grease of Example 1 satisfying the predetermined conditions was evaluated as good or very good in all the results of the tests A to C. Example 2
Although inferior to Example 1, the durability of the bearing was significantly improved as compared with the existing grease. In Example 3, the oil separation rate and the vibration value were good, and the durability was also good. Example 4
The oil separation rate, adhesion, bearing temperature rise and vibration were small, and durability was good.

Next, in the bearing of the rolling bearing for the spindle,
The temperature difference of the outer race and the bearing life will be described with reference to examples and comparative examples.

Embodiment 5 The grease used in the above-mentioned Embodiment 1 was replaced with an inner ring inner diameter φ100 mm × outer ring outer diameter φ150 mm ×
6 ml of an angular contact ball bearing for a spindle having a width of 24 mm was uniformly filled in the bearing internal space. The main shaft of the machine tool was inserted into the inner ring of this bearing, and was mounted so that the constant pressure preload became 2.5 kN.

While increasing the rotation speed of the obtained spindle rolling bearing from 2000 rpm to 12000 rpm, the temperatures (° C.) of the inner ring and the outer ring were appropriately measured, and the temperature difference between the inner and outer rings was examined. It is shown in the table.

In order to examine the durability of the bearing in a high-speed rotation state, the above-mentioned angular contact ball bearing for a spindle was
Continuous rotation was performed at 000 rpm, and the time until the vibration increased was measured as the durability time.

As a result of measurement using a plurality of test bearings under the same conditions, the angular contact ball bearing for a spindle of Example 5 was found to have a durability of 2200 to 2500 hours.

Comparative Example 5 A grease having a consistency of 280 was prepared using barium complex (Ba composite soap) as a thickener, an ester oil having a kinematic viscosity at 40 ° C. of 20 cSt and a dropping point of> 200 ° C. With respect to this grease, the temperature (° C.) of the inner ring and the outer ring was appropriately measured while increasing the rotation speed from 2000 rpm to 12000 rpm under the same conditions as in Example 5, and the temperature difference between the inner and outer rings was examined. Are also shown in the figure.

In order to examine the durability of the bearing in a high-speed rotation state, the angular contact ball bearing for the spindle was continuously rotated at 11,000 rpm as in the case of the fifth embodiment, and the time until the vibration increased became the same as the durability time. The measurement was performed using a plurality of test bearings under the conditions.

As a result, the rolling bearing of Comparative Example 5 was found to have a durability time of about 600 hours.

As is clear from the results shown in FIG. 7, the temperature of both the inner and outer rings of the angular contact ball bearing for spindle of Example 5 was relatively higher than that of Comparative Example 5.
In particular, it was considered that this tendency was remarkable when rotating at a high speed of 6000 rpm or more. It is considered that the grease moved to the outer ring side due to centrifugal force and shear frictional force acted. It was thought that the temperature difference with the inner ring side would disappear.

As described above, in the angular contact ball bearing for a spindle according to the fifth embodiment, since the temperature difference between the inner ring and the outer ring is small at the time of high-speed rotation, the inner ring and the outer ring expand to the same extent and the bearing gap does not decrease much. Therefore, when installing the machine tool spindle (spindle), the built-in preload (initial preload) can be set sufficiently high, and the fixing force between the spindle and bearing is increased accordingly, producing a highly rigid machine tool spindle. can do.

As described above, the durability of the comparative example 5 in the high-speed rotation state (time) of 600 hours is different from that of the comparative example 5 in that it can be used for a long continuous rotation of 2000 hours or more. It turned out with low vibration and was found to show remarkably excellent durability.

[0074]

As described above, the invention relating to the grease for a high-speed rolling bearing according to the present invention makes the viscosity (kinematic viscosity) of the base oil relatively high within a predetermined range and employs a specific type of thickener. In addition, since the grease is limited to high-speed rolling bearing applications, the rotational torque of the rolling bearing and the temperature rise of the bearing do not become higher than when conventional grease is used, and the grease in the rolling bearing due to centrifugal force during high-speed rotation. And its base oil is excellent in durability without being scattered outside of the bearing, and is an excellent high-speed rolling bearing grease capable of suppressing the vibration of the rolling bearing at a high speed rotation.

In the invention relating to the rolling bearing for a spindle according to the present invention, the viscosity (kinematic viscosity) of the base oil is set to a relatively high predetermined range and a specific kind of thickener is employed. And exhibits excellent rotational characteristics of low vibration and a long service life. Since the temperature difference between the inner ring and the outer ring at the time of high-speed rotation is small, this spindle rolling bearing can sufficiently increase the pressure (initial preload) at which the main shaft and the inner ring are fitted when the main shaft is mounted so that high rigidity can be obtained. There is also an advantage that it is a rolling bearing for a spindle which can be mounted on a spindle.

[Brief description of the drawings]

FIG. 1 is a chart showing a bearing temperature rise and vibration in an evaluation test A of an example and a comparative example.

FIG. 2 is a table showing life times of evaluation tests A of Examples and Comparative Examples.

FIG. 3 is a table showing oil separation rates of evaluation tests B of Examples and Comparative Examples.

FIG. 4 is a cross-sectional view illustrating a main part of an apparatus for examining adhesion of a test grease.

FIG. 5 is a chart showing grease adhesion rates in evaluation tests C of Examples and Comparative Examples.

FIG. 6 is a sectional view of a main part of an angular contact ball bearing.

FIG. 7 is a table showing the relationship between the temperature of the inner and outer rings and the rotation speed in Example 5 and Comparative Example 5.

[Explanation of symbols]

 Reference Signs List 1 steel ball 2, 6 inner ring 3, 4 outer ring 5 grease reservoir 7 retainer 8 main shaft 9 jig 10 ring 11 test grease

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10N 40:02 50:10 (72) Inventor Kenji Fujii 3066 Oyumida, Ogata, Oaza, Kuwana-shi, Mie N.N. In-company (72) Inventor Sato Sato 3066 Oyumida, Oaza, Tozai, Kuwana-shi, Mie Inside NTN Corporation

Claims (6)

[Claims] 1. A kinematic viscosity at 40 ° C. of 30 to 60 cSt.
Grease for high-speed rolling bearings consisting of grease in which an aliphatic urea-based thickener is blended with the above base oil. 2. The compounding amount of the aliphatic urea thickener is:
The grease for a high-speed rolling bearing according to claim 1, wherein the compounding amount is such that the mixing consistency (JIS K2220 5.3) of the grease is 230 to 280. 3. The compounding amount of the aliphatic urea thickener is:
The grease for a high-speed rolling bearing according to claim 1 or 2, wherein the amount of the oil separation is 1 to 10% by weight when a centrifugal force of 2500 G is applied to the grease for 4.5 hours. 4. The base oil is a synthetic hydrocarbon oil, a polyol ester oil or a mixed oil thereof.
3. The grease for a high-speed rolling bearing according to any one of 3. 5. A kinematic viscosity at 40 ° C. of 30 to 60 cSt.
A grease is prepared by blending an aliphatic urea-based thickener so that the mixing consistency (JIS K2220 5.3) is 230 to 280 with the base oil described above, and the grease is sealed in a rolling bearing. Rolling bearing. 6. The spindle rolling bearing according to claim 5, wherein the rolling bearing is an angular ball bearing or a cylindrical roller bearing.