JP2003013960A - High speed rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize low torque and low heat generation and improve a seizure-resistant property and wear-resistant property at high speed rotation. SOLUTION: In an angular contact ball bearing used for high speed rotation in which a plurality of balls are arranged between an inner ring 11 and outer ring 12 via a retainer 14 and at least one of surfaces of their base material among an inner ring raceway, an outer ring raceway, balls 13, and a retainer 14 is formed by steel and a, DLC film is also formed on the surface of the base material, the DLC film is provided with an intermediate layer made of metal components, a compound layer made of a carbon component, and a carbon layer. The compound layer is a graded layer in which composition is consecutively changed from the intermediate layer to the carbon layer, and plastic deformation hardness of the DLC film is set at 8 to 35 GPa.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing for high speed rotation used for a spindle of a machine tool or the like, and particularly to a small oil lubrication environment such as grease lubrication, oil air lubrication, oil mist lubrication or direct injection micro oil lubrication. The present invention relates to a rolling bearing for high speed rotation suitable for use below.

[0002]

2. Description of the Related Art In recent years, in machine tools, there is a strong demand for high-speed spindles in order to improve machining efficiency, and along with this, the operating speed of rolling bearings for spindles is also increasing. At the same time, there is a demand for lower bearing heat generation in order to improve machining accuracy.
Generally, when an angular ball bearing rotates at a high speed, a large slip occurs due to a spin motion or a gyro motion at a contact portion between a rolling element (ball) and a raceway surface. In addition, the contact surface pressure between the ball and the raceway surface increases due to the centrifugal force acting on the inner ring and the balls and the reduction of the bearing internal clearance due to the temperature difference between the inner and outer rings.
Such slippage and increase in surface pressure at the contact portion cause various problems such as temperature rise due to heat generation, seizure, and progress of excessive wear.

As a measure for suppressing the above-mentioned problems, the diameter of the ball is reduced or the material of the ball is made of lightweight ceramics to reduce the increase in the surface pressure due to the centrifugal force of the ball. Further, Japanese Patent Laid-Open No. 62-24025 discloses a method of suppressing the change in the bearing internal clearance by using a material of the inner ring having a smaller linear expansion coefficient than the material of the outer ring.

Further, Japanese Patent Laid-Open No. 2000-145749 and Japanese Patent Laid-Open No. 11-270564 disclose a method of realizing a bearing of ultra-high speed, high rigidity and low heat generation by optimizing the internal specifications of the bearing. It is disclosed. When the rolling bearing having such measures is applied to the spindle of a machine tool or the like, the DmN value indicating the allowable rotation speed becomes (Dm:
Rolling element pitch diameter mm, N: rotation speed min ^-1 ) is 3 at maximum
It is said that it can operate up to about 500,000.

[0005]

However, the operating speed of the rolling bearing tends to increase more and more, and it is difficult to further increase the speed and reduce the heat generation only by the technique disclosed above. In particular, machine tool bearings are used with a small amount of oil lubrication such as grease lubrication, oil air lubrication, oil mist lubrication, or direct injection type micro oil lubrication for the purpose of reducing torque and heat generation. That is, lubrication is performed with a slight amount of lubricating oil under high speed rotation. Therefore, when the DmN value is high-speed rotation exceeding about 2 million, the oil film is broken at the contact portion between the ball and the raceway surface, and the ball and the raceway surface are likely to come into direct contact with each other, and damage such as seizure or abrasion is likely to occur. There is a problem.
In particular, grease lubrication has a lower allowable rotation speed than oil-air lubrication or oil mist lubrication because an oil film is less likely to be formed.

The present invention has been made in order to eliminate such inconvenience, and it is of course possible to realize low torque and low heat generation as well as seizure resistance and wear resistance under high speed rotation. An object of the present invention is to provide a rolling bearing for high speed rotation, which can be improved.

[0007]

In order to achieve the above object, the invention according to claim 1 is such that a plurality of rolling elements are arranged between an inner ring and an outer ring via a cage and an inner ring raceway. Surface, outer ring raceway surface, at least one of the rolling elements and the cage surface of the base material is made of steel, and a diamond-like carbon film is formed on the surface of the base material. The diamond-like carbon film includes a metal component intermediate layer, a carbon component composite layer, and a carbon layer, and the composite layer has a gradient in which the composition continuously changes from the intermediate layer toward the carbon layer. Layer, and the plastic deformation hardness of the diamond-like carbon film is 8 to 3
It is characterized by being 5 GPa.

According to a second aspect of the present invention, in the first aspect, the diamond-like carbon film has an equivalent elastic modulus of 100 to 280 GPa. According to a third aspect of the present invention, in the first or second aspect, the diamond-like carbon film has a thickness of 0.1 to 5 μm. The invention according to claim 4 is claim 1
In any one of (1) to (3), it is characterized in that it is used in a small amount oil lubrication environment such as grease lubrication, oil air lubrication, oil mist lubrication or direct injection type minute amount oil lubrication.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the material of the rolling element is ceramics. The invention according to claim 6 is characterized in that, in any one of claims 1 to 5, the base material of the outer ring and / or the inner ring is heat-resistant bearing steel. The invention according to claim 7 is characterized in that, in any one of claims 1 to 6, the invention is used for a spindle of a machine tool.

Here, the metal component of the intermediate layer is not particularly limited as long as it contains the components of the base steel and the atomic radii of the constituent elements are similar. For example, Cr, W, T
Examples thereof include i, Si, Ni, Fe, Co and the like. Among them, when the base material is stainless steel or bearing steel, Cr, Ni
Etc. are desirable, and Si, W, C depending on the steel content
o or the like can be appropriately selected.

Diamond-like carbon (hereinafter referred to as DL
Examples of the film forming method (referred to as C) include non-equilibrium magnetron sputtering, pulsed laser arc vapor deposition, and plasma CVD. Among them, non-equilibrium magnetron sputtering in which the equivalent elastic modulus and plastic deformation hardness can be controlled independently Law is desirable. The plastic deformation hardness of the DLC film is measured by a (micro) Vickers hardness meter,
It is desirable to use a micro hardness meter and nano-intensity data that can be controlled by a capacitance type. The indentation at this time must be within the film thickness range of the DLC film. Similarly, for the measurement of the equivalent elastic coefficient, it is desirable to use a micro hardness meter and nano-intensity data and to find the equivalent elastic coefficient from the elastic deformation amount of the load-unload curve.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory cross-sectional view for explaining an angular contact ball bearing, which is an example of an embodiment of the present invention,
2 is a graph showing the relationship between the equivalent elastic modulus of the DLC film, the plastic deformation hardness and the fracture strength, FIG. 3 is a graph showing the relationship between the element ratios of carbon, chromium and iron and the DLC film thickness, and FIG. FIG. 5 is an enlarged cross-sectional view of the DLC film, FIG. 5 is an explanatory cross-sectional view for explaining a cylindrical roller bearing which is another embodiment of the present invention, and FIGS. 6 to 9 are shaft rotation speeds in comparative examples and examples of the present invention. 10 is a graph showing the relationship with the outer ring temperature rise, FIG. 10 is a schematic view of the bearing rotation tester, and FIGS. 11 and 12 are graphs showing the relationship between the shaft rotation speed and the outer ring temperature rise in the comparative example and the present invention example. is there.

First, referring to FIG. 1, an angular ball bearing (rolling bearing for high speed rotation) which is an example of an embodiment of the present invention will be described. This angular ball bearing 10 includes an inner ring 11 and an outer ring 12. A plurality of ceramic balls (rolling elements) 13 are provided between the inner ring 1 and the cage 14.
1 and the outer ring 12 are made of steel, and the inner ring 11 has a rotating shaft 1
It is fitted in 5. A DLC film is formed on the raceway surface of the inner ring 11 and the raceway surface of the outer ring 12. The cage 14 is of an outer ring guide type.

This DLC film is formed of Cr,
A graded composition in which the interface between the intermediate layer made of a metal component such as W, Ti, and Si and the carbon layer is eliminated, and the composition continuously changes from the intermediate layer to the carbon layer between the intermediate layer and the carbon layer. Forming a composite layer (gradient layer) and having a plastic deformation hardness of 8 to 3
It is set to 5 GPa. As a method for forming the DLC film, there are a non-equilibrium sputtering method and a plasma CVD method. For example, an unbalanced magnetron sputtering apparatus (UBMS apparatus 504) manufactured by Kobe Steel, Ltd., a hot cathode plasma manufactured by Shinko Seiki Co., Ltd. It is preferable to form the DLC film using a CVD device (PIG type thin film forming device).

For example, in the UBMS apparatus 504, a plurality of targets used for sputtering are mounted and the sputtering power sources for the targets of the intermediate layer and the carbon layer are independently controlled, thereby continuously reducing the sputtering efficiency of the intermediate layer.
Increasing the sputtering efficiency of the carbon layer target to form a composite layer. The sputtering power source of the target is controlled using a DC power source, and a bias voltage is applied to the base material to simultaneously control the sputtering efficiency. The film thickness of the DLC film can be controlled by the sputtering time, and the film thickness ratio of the intermediate layer and the composite layer and the total film thickness can be accurately controlled. If a hydrocarbon-based gas such as argon, hydrogen or CH ₄ is introduced during the formation of this DLC film, the sliding resistance of the DLC film surface can be controlled. A suitable film composition can be formed.

FIG. 2 shows the equivalent elastic modulus and plastic deformation of the DLC film.
The relationship between hardness and breaking strength is shown. Regarding the breaking strength
2GPa using a thrust durability tester (not shown)
Under the condition that the Hertzian contact stress of
Number is 10⁹It is evaluated by the presence or absence of peeling of the DLC film at the time of reaching
I paid. Moreover, the test condition is a rotation speed of 8000 mi.
n ^-1, With grease lubrication.

As is apparent from FIG. 2, the plastic deformation hardness of the DLC film is 8 to 35 GPa, which is harder than the base material, and DL.
High breaking strength could be obtained in a region where the equivalent elastic modulus of the C film was 100 to 280 GPa, which was smaller than the equivalent elastic modulus of the base material. If the plastic deformation hardness of the DLC film is less than 8 GPa, the wear becomes large, and if it exceeds 35 GPa, brittle fracture easily occurs. Also, the equivalent elastic modulus of the DLC film is 10
If it is less than 0 GPa, the surface hardness of the DLC film is reduced and wear is likely to occur with a large contact stress, resulting in 280 GPa.
If it exceeds, the equivalent elastic modulus of the DLC film becomes larger than the equivalent elastic modulus of the base material (steel), and the steel deforms before the DLC film in response to a large contact stress.
The problem that the LC film is destroyed occurs.

The ratio between the plastic deformation hardness (H) and the equivalent elastic modulus (E) is preferably (H / E) of 0.08 to 0.16, and the composite layer has a total thickness of the DLC film. 1 to 99% (more preferably 5 to 50%), and the carbon element ratio of the outermost surface of the DLC film is 100%. The equivalent elastic modulus and the plastic deformation hardness were measured by using a micro hardness meter manufactured by Fischer Co., and the equivalent elastic modulus was measured by a pushing load of 20 m.
It can be determined from the load-unload curve under the conditions of N and indentation depth of 0.15 to 0.5 μm. In addition, when measuring a thin film of 1 μm or less, the pushing load is 0.4 to 20.
It is desirable to set it appropriately to mN so that the indentation depth is at least within the range of the DLC film.

Besides, the equivalent elastic modulus can be similarly obtained by using a micro hardness measuring device manufactured by Elionix. The thickness of the composite layer can be measured using an X-ray photoelectron spectroscopy analyzer (hereinafter referred to as XPS). It irradiates the sample surface with X-rays and obtains the information (qualitative and quantitative) of the elements on the sample surface and the binding state by the energy analysis of the photoelectrons emitted from the outermost surface (about several angstroms) of the sample. It is possible to analyze the distribution state of elements in the depth direction (that is, below the sample surface) by performing measurement while sputtering the sample surface using an argon ion gun.

FIG. 3 shows the element ratios of carbon, chromium and iron and DL.
The relationship with the C film thickness is shown. The thickness of the composite layer of the DLC film formed by the UBMS device 504 is measured by, for example, XP.
The depth profile of the sample was taken using S, and the change in the photoelectron intensity of carbon, chromium, and iron in the DLC film was expressed by the element ratio to identify the composite layer, and the etching rate was 30 nm / mi.
n is converted into the thickness of the composite layer from the etching rate and the time required for it.

The thickness of the DLC film is 0.1 to 5 μm.
Is desirable, and preferably 0.5 to 3 μm. When the thickness of the DLC film is smaller than 0.1 μm, the surface of the base material is exposed to a large extent and the performance of the DLC film is reduced. As a result, the effect of improving the slidability and wear resistance is reduced. On the other hand, if the thickness of the DLC film is thicker than 5 μm, the internal stress in the film increases and the adhesion with the base material is impaired.

The metal material of the bearing ring, which is the base material on which the DLC film is applied, that is, the bearing steel, is a material in which a secondary hardening precipitation type eutectic carbide is formed (for example, high speed steel, semi-high speed steel, martensite base material). (Stainless steel), and a material in which tempering resistance is improved by constituent element components and dimensions are stabilized (material conforming to high carbon chromium steel) are preferable. For example, in the former case, SKD, SKH, SUS440C
In the latter case, as the heat-resistant bearing steel, for example, at least Si: 0.7 to 1.5 wt%, Cr:
0.5% to 2.0% by weight, Mo: 0.5% to 2.0% by weight, and other materials whose surface has been carbonitrided in advance M5
0, M50NIL material is specifically mentioned.

It is also possible to use general bearing steel (SUJ2) as the metal material of the bearing ring, and in that case,
Tempering temperature is 120 to 400 ° C, preferably 180
˜330 ° C., and more preferably 180 to 260 ° C. If the tempering temperature is lower than 120 ° C, the bearing is deformed by the DLC film treatment temperature (120 to 130 ° C), and if it is higher than 400 ° C, the surface hardness is remarkably reduced.
Therefore, in order to prevent the bearing from being deformed by the film forming process of the DLC film and to give the surface hardness of HRC 50 or more, it is preferable that the tempering temperature range is within the above range.

Among the nitriding treatments, gas nitriding, ion nitriding, ion implantation and the like are suitable as the base treatment of the base material on which the DLC film is formed, and it is desirable to appropriately control the nitrogen content. For example, the thickness of these nitride layers is 0. 1 to 60 μm is desirable, and the nitrogen concentration is 0. Ten . 8% is preferred. 0
． If it is less than 1%, the sliding property of the surface layer is poor, while 0. 8
%, The surface nitrogen concentration is high, and the adhesion of the reaction deposit to the base is impaired.

The reason why the DLC film having the above structure is effective is that it has the same surface hardness as ceramics such as silicon nitride used for rolling elements, and is more resistant to seizure and wear than the metal of the base material of the race. This is because it has excellent properties, excellent lubricating properties, a low coefficient of friction, and high fracture strength. Further, the above DLC is used for rolling bearings that require low torque and low heat generation performance.
By forming the film, the performance can be improved.

Then, the angular contact ball bearing having the above-mentioned DLC film formed on the inner and outer races is mounted on a spindle of a machine tool or the like,
A small amount of oil such as grease lubrication, oil-air lubrication, oil mist lubrication, or direct injection micro oil lubrication to reduce the shearing resistance and stirring resistance of lubricating oil and realize low torque and low heat generation under high-speed rotation. When used in a lubricated environment,
Even if the oil film ruptures at the contact area between the ball and raceway surface and the ball and raceway surface come into direct contact, seizure is achieved due to the low torque and low heat generation characteristics of the DLC film itself and the effect of improving seizure resistance and wear resistance. It is possible to favorably prevent damage such as abrasion and abrasion.

In the above embodiment, the inner and outer races 11,
Although the case where the DLC film is formed on the raceway surface of 12 is taken as an example, the DLC film may be formed on the entire outer diameter surface of the inner ring 11 and the entire inner diameter surface of the outer ring 12 as necessary. ,
The DLC film may be formed on only one of the outer rings 12. Further, the DLC film may be formed on the entire surface of the inner ring 11 and the entire surface of the outer ring 12, and the DLC film may be formed on the cage 14.
Furthermore, using the steel rolling element 13, DL
A C film may be formed.

Further, in the above embodiment, the angular ball bearing is used as an example of the rolling bearing for high speed rotation, but the present invention may be applied to a cylindrical roller bearing as shown in FIG. 5 instead. . In this cylindrical roller bearing (rolling bearing for high speed rotation) 20, a plurality of rollers (rolling elements) 23 are arranged between an inner ring 21 and an outer ring 22 via a cage 24,
The inner ring 21, the outer ring 22, the rollers 23, and the cage 24 are all made of steel so that the inner ring 21 is fitted on a rotating shaft (not shown). The raceway surface and the flange 25 end surface provided on the outer diameter surface of the inner ring 21, the raceway surface provided on the inner diameter surface of the outer ring 22, the guide surface of the cage 24, the roller 2
A DLC film is formed on the entire surface of No. 3 and the outer diameter surface of the cage 24. The cage 24 is of an outer ring guide type.

The cylindrical roller bearing 20 having such a structure is mounted on a main shaft of a machine tool or the like to reduce shear resistance and agitation resistance of lubricating oil so as to realize low torque and low heat generation under high speed rotation. When used in a small amount oil lubrication environment such as lubrication, oil air lubrication, oil mist lubrication, or direct injection type minute amount oil lubrication, the contact portion between the roller 23 and the flange 25 end surface, the cage 24 and the guide surface of the outer ring 22 Contact part, roller 2
The oil film ruptures at the contact point between the raceway surface and the roller 3
3. Even if the cage 24 and the bearing ring are in direct contact with each other, as in the above-described embodiment, the low torque and low heat generation characteristics of the DLC film itself and the effect of improving seizure resistance and wear resistance are combined to prevent seizure or seizure. It is possible to favorably prevent damage such as abrasion. The rest of the configuration, functions, and effects are substantially the same as those of the above-mentioned embodiment, and therefore their explanations are omitted.

[0030]

EXAMPLES FIGS. 6 to 8 show experimental results of measuring the temperature rise (outer ring temperature rise) and seizure limit of an angular ball bearing in oil-air lubrication in order to confirm the effect of the DLC film of the present invention. There is. Table 1 shows the test pieces (bearing specifications) used in this experiment. The temperature rise corresponds to the amount of heat generated by the entire angular ball bearing.

[0031]

[Table 1]

In this experiment, an inner ring made of SUJ2 and having an inner diameter of 100 mm, an outer ring made of SUJ2 and having an outer diameter of 160 mm, and a ceramic rolling element made of Si ₃ N ₄ (rolling element pitch diameter: 132.5 mm) A plurality of angular contact ball bearings each having and are used as test specimens. The cage uses an outer ring guide system. FIG. 10 shows an outline of the test apparatus. In FIG. 10, reference numeral 31 is a rolling bearing for high speed rotation as a specimen,
The left side is an angular ball bearing, and the right side is a cylindrical roller bearing (described later). Further, reference numeral 32 is a main shaft, 33 is a pulley for transmitting driving force, and 34 is a thermocouple for temperature measurement.

In the experiments shown in FIG. 6 to FIG. 8, as a test piece, each angular ball bearing was mounted along the axial direction with 1
A load of 470 N is applied, and oil-air lubrication using VG22 oil as a lubricant is used as a method of lubricating the angular ball bearing. The VG22 oil is a lubricating oil defined in JIS (Japanese Industrial Standard) K2211, etc. In addition, the value of the outer ring temperature rise on the vertical axis in FIGS. 6 to 8 is converted into the outer ring temperature rise (outer ring temperature-outside air temperature) by measuring the outer ring temperature by bringing the thermocouple 34 into contact with the outer ring outer diameter surface. Is shown. Regarding the lubrication condition, 0.
Experiments were carried out on three types of 1 cc / hour (FIG. 6), 0.675 cc / hour (FIG. 7) and 5.4 cc / hour (FIG. 8) using the invention product and the conventional product (comparative example).

The present invention N1 shown in FIGS. 6 to 8 is a UBM manufactured by Kobe Steel, Ltd. only on the inner ring raceway of an angular ball bearing.
The DLC film is formed using the S device 504.
The present invention O1 shown in FIGS. 6 to 8 is the UBM manufactured by Kobe Steel, Ltd. on the inner ring raceway surface and the outer ring raceway surface of the angular ball bearing.
The DLC film is formed using the S device 504.

The present invention P1 shown in FIGS. 6 to 8 is one in which a DLC film is formed only on the inner ring raceway surface of an angular ball bearing by using a PIG type thin film manufacturing apparatus manufactured by Shinko Seiki.
The invention Q1 shown in FIGS. 6 to 8 is one in which a DLC film is formed on the inner ring raceway surface and the outer ring raceway surface of an angular ball bearing by using a PIG type thin film manufacturing apparatus manufactured by Shinko Seiki Co., Ltd.

Comparative Example A1 shown in FIGS. 6 to 8 is a DLC.
It is a conventional angular contact ball bearing without a film. 6-
As is clear from FIG. 8, the products N1, O1, P1 of the present invention,
Q1 shows almost the same performance, and Comparative Example A1
It can be seen that the temperature rise (outer ring temperature rise) is lower and the seizure limit is also higher than that of No. Therefore, it is clear that the product of the present invention is effective for increasing the speed and decreasing the temperature of the angular ball bearing. And especially D
The difference becomes clear in the region where the mN value exceeds 2 million.

FIG. 9 shows the experimental results of measuring the temperature rise (outer ring temperature rise) and seizure limit of the angular contact ball bearing in grease lubrication. Table 2 shows the specimens used at this time. The temperature rise corresponds to the amount of heat generated by the entire angular ball bearing.

[0038]

[Table 2]

In this experiment, an inner ring made of SUJ2 and having an inner diameter of 65 mm, an outer ring made of SUJ2 and having an outer diameter of 100 mm, and a ceramic rolling element made of Si ₃ N ₄ (rolling element pitch diameter: 81.65 mm) A plurality of angular contact ball bearings each having and are used as test specimens. The cage uses an outer ring guide system. In the experiment shown in FIG. 9, the load is applied according to the preload setting amount of the fixed position preload when the respective angular ball bearings as the test pieces are combined (bearing axial rigidity when assembled: 98 N / μm), and the angular ball As a lubrication method for bearings, ISOFLEX N made by NOK CRYVA
Grease lubrication using BU15 (enclosed amount: 15% of bearing space volume) as a lubricant is used.

Further, in FIG. 9, the result of measuring the outer ring temperature by bringing a thermocouple into contact with the outer ring outer diameter surface is shown in terms of the outer ring temperature rise (outer ring temperature-outside air temperature). The present invention R1 shown in FIG. 9 uses a UBMS device 504 manufactured by Kobe Steel, Ltd. for the DLC only on the inner ring raceway surface of the angular contact ball bearing.
A film is formed. The present invention S1 shown in FIG. 9 is one in which a DLC film is formed on the inner ring raceway surface and the outer ring raceway surface of an angular ball bearing by using a UBMS device 504 manufactured by Kobe Steel.

The present invention T1 shown in FIG. 9 is one in which a DLC film is formed only on the inner ring raceway surface of an angular ball bearing using a PIG type thin film manufacturing apparatus manufactured by Shinko Seiki. The present invention U1 shown in FIG. 9 is one in which a DLC film is formed on the inner ring raceway surface and the outer ring raceway surface of an angular ball bearing by using a PIG type thin film manufacturing apparatus manufactured by Shinko Seiki. Comparative example B shown in FIG.
Reference numeral 1 is a conventional angular contact ball bearing without a DLC film.

From FIG. 9, the products R1, S1, T1, U of the present invention are shown.
It can be seen that in No. 1, the temperature rise (outer ring temperature rise) is lower and the seizure limit is higher than in Comparative Example B1.
Further, the products R1, S1, T1, and U1 of the present invention all show substantially the same performance, and even if the DLC film is applied only to the inner ring raceway, it is effective for increasing the speed and lowering the temperature of the angular ball bearing. It turns out that

FIG. 11 shows the experimental results of measuring the temperature rise (outer ring temperature rise) and the seizure limit of the cylindrical roller bearing in oil-air lubrication. Table 3 shows the test pieces (bearing specifications) used at this time. The temperature rise corresponds to the amount of heat generated by the entire cylindrical roller bearing.

[0044]

[Table 3]

In this experiment, Si: 0.7-1.
5% by weight, Cr: 0.5 to 2.0% by weight, Mo: 0.5
~ 2.0 wt%, made of heat-resistant bearing steel with carbonitrided surface in advance, inner ring with 70 mm inner diameter, outer ring with the same material as the inner ring and 110 mm outer diameter, the same as the inner ring A plurality of cylindrical roller bearings each having a rolling element of material (rolling element pitch diameter: 91 mm) are used as test pieces. The cage uses an outer ring guide system.

In the experiment shown in FIG. 11, the radial clearance at the time of assembling each cylindrical roller bearing as a test piece was adjusted to 0 μm. The lubrication method uses oil-air lubrication using VG22 oil as a lubricant. In addition, VG22 oil is JIS (Japanese Industrial Standard) K221
It is a lubricating oil defined as 1 and the like. Further, the outer ring temperature rise on the vertical axis in FIG. 11 is shown by converting the result of contacting the outer ring outer diameter surface with the thermocouple 34 to measure the outer ring temperature to the outer ring temperature rise (outer ring temperature-outside air temperature). Regarding the lubrication condition, an experiment was performed using the invention product and the conventional product (comparative example) at 0.0375 cc / hour.

The present invention N2 shown in FIG. 11 is a UB manufactured by Kobe Steel Ltd. on the inner ring raceway surface and flange end surface of the cylindrical roller bearing.
The DLC film is formed using the MS device 504. In the invention O2 shown in FIG. 11, a DLC film is formed on the inner ring raceway surface, the flange end surface and the outer ring raceway surface of the cylindrical roller bearing by using the UBMS apparatus 504 manufactured by Kobe Steel Ltd.

The present invention P2 shown in FIG. 11 is a PIG manufactured by Shinko Seiki Co., Ltd. on the inner ring raceway surface and flange end surface of the cylindrical roller bearing.
The DLC film is formed by using the film forming apparatus. The present invention Q2 shown in FIG. 11 is a P manufactured by Shinko Seiki Co., Ltd. on the inner ring raceway surface, flange end surface and outer ring raceway surface of the cylindrical roller bearing.
A DLC film is formed using an IG type thin film manufacturing apparatus.

Comparative Example A2 shown in FIG. 11 is a conventional cylindrical roller bearing not coated with a DLC film. From FIG. 11, all of the products N2, O2, P2, and Q2 of the present invention show substantially the same performance, and the temperature rise (outer ring temperature rise) is lower and the seizure limit is higher than the comparative product A2. I understand that. Therefore, it is clear that the product of the present invention is effective for increasing the speed and lowering the temperature of the cylindrical roller bearing.

FIG. 12 shows the experimental results of measuring the temperature rise (outer ring temperature rise) and seizure limit of the cylindrical roller bearing in grease lubrication. Table 4 shows the specimens (bearing specifications) used at this time. The temperature rise corresponds to the amount of heat generated by the entire cylindrical roller bearing.

[0051]

[Table 4]

In this experiment, Si: 0.7-1.
5% by weight, Cr: 0.5 to 2.0% by weight, Mo: 0.5
~ 2.0 wt%, made of heat-resistant bearing steel with carbonitrided surface in advance, inner ring with 70 mm inner diameter, outer ring with the same material as the inner ring and 110 mm outer diameter, the same as the inner ring A plurality of cylindrical roller bearings each having a rolling element of material (rolling element pitch diameter: 91 mm) are used as test pieces. The cage uses an outer ring guide system.

In the experiment shown in FIG. 12, the radial clearance at the time of assembling each cylindrical roller bearing as a test piece was set to 0 μm. As the lubrication method, grease lubrication using Isoflex NBU15 (encapsulated amount: 10% of the bearing space volume) manufactured by NOK CLUVA as a lubricant is used. Further, the outer ring temperature rise on the vertical axis of FIG. 12 is shown by converting the result of contacting the outer ring outer diameter surface with the thermocouple 34 to measure the outer ring temperature to the outer ring temperature rise (outer ring temperature-outside air temperature).

The present invention R2 shown in FIG. 12 is a UB manufactured by Kobe Steel, Ltd. on the inner ring raceway surface and the flange end surface of the cylindrical roller bearing.
The DLC film is formed using the MS device 504. The present invention S2 shown in FIG. 12 has U made by Kobe Steel Ltd. on the inner ring raceway surface, flange end surface and outer ring raceway surface of the cylindrical roller bearing.
A DLC film is formed using the BMS device 504.

The present invention T2 shown in FIG. 12 is one in which a DLC film is formed on the inner ring raceway surface and flange end surface of a cylindrical roller bearing using a PIG type thin film manufacturing apparatus manufactured by Shinko Seiki Co., Ltd.
The invention U2 shown in FIG. 12 is a PIG manufactured by Shinko Seiki Co., Ltd. on the inner ring raceway surface, the flange end surface and the outer ring raceway surface of the cylindrical roller bearing.
The DLC film is formed by using the film forming apparatus.

Comparative Example B2 shown in FIG. 12 is a conventional cylindrical roller bearing not coated with a hard DLC film. It can be seen from FIG. 12 that the products R2, S2, T2, and U2 of the present invention have a lower temperature rise (outer ring temperature rise) and a higher seizure limit than those of the comparative example B2. The product R2 of the present invention,
S2, T2, and U2 all show almost the same performance, and even if only the inner ring (the inner ring raceway surface and the flange end surface) is coated with a DLC film, the cylindrical roller bearing can be speeded up and the temperature can be lowered. On the other hand, it turns out that it is effective.

[0057]

As is apparent from the above description, according to the present invention, it is possible to realize low torque and low heat generation, and to improve seizure resistance and wear resistance under high speed rotation. The effect that can be achieved is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view for explaining an angular ball bearing that is an example of an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the equivalent elastic modulus, plastic deformation hardness, and fracture strength of a DLC film.

FIG. 3 is a graph showing the relationship between the element ratios of carbon, chromium and iron and the DLC film thickness.

FIG. 4 is an enlarged cross-sectional view of a DLC film.

FIG. 5 is an explanatory sectional view for explaining a cylindrical roller bearing which is another embodiment of the present invention.

FIG. 6 is a graph showing a relationship between a shaft rotation speed and an outer ring temperature increase in a comparative example and an example of the present invention.

FIG. 7 is a graph showing the relationship between the shaft rotation speed and the outer ring temperature rise in the comparative example and the present invention example.

FIG. 8 is a graph showing the relationship between the shaft rotation speed and the outer ring temperature rise in the comparative example and the present invention example.

FIG. 9 is a graph showing the relationship between the shaft rotation speed and the outer ring temperature rise in the comparative example and the present invention example.

FIG. 10 is a schematic view of a bearing rotation tester.

FIG. 11 is a graph showing the relationship between the shaft rotation speed and the outer ring temperature rise in the comparative example and the present invention example.

FIG. 12 is a graph showing the relationship between the shaft rotation speed and the outer ring temperature rise in the comparative example and the present invention example.

[Explanation of symbols]

10 ... Angular contact ball bearing (Rolling bearing for high speed rotation) 20 ... Cylindrical roller bearing (high speed rolling bearing) 11, 21 ... Inner ring 12, 22 ... Outer ring 13 ... Ball (rolling element) 14, 24 ... Cage 23 ... Roller (rolling element)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B23B 19/02 B23Q 1/26 D (72) Inventor Dai Kanano 1-5 Kumeiuma Kugenuma, Fujisawa City, Kanagawa Prefecture No. 50 In NSK Ltd. (72) Inventor Hirotoshi Aramaki 1-5-50 Shinmei Kugenuma, Fujisawa-shi, Kanagawa F-Term (reference) 3C011 FF06 3C045 FD12 FD18 3C048 BB14 CC04 DD13 EE02 3J101 AA02 AA32 AA54 AA62 BA10 BA50 BA70 DA05 EA03 EA44 EA63 EA78 FA31 FA33 FA60 GA31

Claims (7)

[Claims] 1. A plurality of rolling elements are arranged between an inner ring and an outer ring via a cage, and a surface of at least one base material of the inner ring raceway surface, the outer ring raceway surface, the rolling elements and the cage. Is a steel, and a rolling bearing for high speed rotation, wherein a diamond-like carbon film is formed on the surface of the base material, wherein the diamond-like carbon film is a composite layer of a metal component intermediate layer and a carbon component. And a carbon layer, the composite layer is a graded layer whose composition continuously changes from the intermediate layer toward the carbon layer, and the diamond-like carbon film has a plastic deformation hardness of 8 to 35 GPa. A rolling bearing for high-speed rotation characterized by 2. The rolling bearing for high speed rotation according to claim 1, wherein the diamond-like carbon film has an equivalent elastic modulus of 100 to 280 GPa. 3. The rolling bearing for high speed rotation according to claim 1, wherein the diamond-like carbon film has a film thickness of 0.1 to 5 μm. 4. The use according to any one of claims 1 to 3, wherein the grease is used in a minute oil lubrication environment such as grease lubrication, oil air lubrication, oil mist lubrication, or direct injection type minute oil lubrication. Rolling bearings for high speed rotation. 5. The rolling bearing for high speed rotation according to claim 1, wherein a material of the rolling element is ceramics. 6. The rolling bearing for high speed rotation according to claim 1, wherein a base material of the outer ring and / or the inner ring is heat-resistant bearing steel. 7. The rolling bearing for high speed rotation according to claim 1, wherein the rolling bearing is used for a spindle of a machine tool.