JP2003294041A - Rolling bearing and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing having long life even under a hostile lubricating condition in which lubrication is made by refrigerating machine oil containing refrigerant. <P>SOLUTION: The rolling bearing is provided with an outer ring 1, an inner ring 2 and a plurality of rolling elements 3 freely rotatably disposed between both rings 1, 2, wherein refrigerating machine oil 5 containing refrigerant filled in a gap inside which the rolling element 3 formed between both rings 1, 2 is provided. No foreign matter whose average diameter exceeding 3 μm exists on the raceway surfaces 1a, 2a of both rings 1, 2 and on the rolling surface 3a of the rolling elements 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing suitable for use in a compressor device of an air conditioner, and a rolling bearing lubricated with a refrigerating machine oil such as polyalkylene glycol (PAG) containing a refrigerant such as CFC. Regarding bearings. Further, the present invention is a rolling bearing used for applications requiring long life and high accuracy, or a rolling bearing used under conditions of high speed and small oil film parameters (low Λ region) under oil lubrication such as oil-air lubrication. The present invention relates to a bearing, and particularly to a rolling bearing which is preferably used for a main shaft of a machine tool and the like. Furthermore, the present invention relates to a method of manufacturing the rolling bearing as described above.

[0002]

2. Description of the Related Art As a lubricant for a rolling bearing used in a compressor device of an air conditioner, a refrigerating machine oil such as PAG in which CFC used as a refrigerant of a compressor device is well dissolved is generally used. Then, the rolling bearing is lubricated by the refrigerating machine oil in which the refrigerant is melted. Further, this refrigerating machine oil is supplied to the lubricated portion by being agitated by a swash plate and splashed.

Conventionally, a rolling bearing used in such a compressor device of an air conditioner has a lubricant and a method of supplying the same (that is, the shape of a cage provided in the rolling bearing) as compared with a normal rolling bearing. Although different, the method of manufacturing the rolling bearing itself was the same as the usual method.

On the other hand, rolling bearings used in machine tools and the like are subject to severer operating conditions year by year due to higher speed and higher efficiency of machine tools. Is increasing.

In particular, with respect to the rolling bearing used for the main spindle of a machine tool, problems such as seizure due to high-speed rotation of the main spindle and high load and early peeling due to inclusion of foreign matter are likely to occur, and the performance of the workpiece Since the processing accuracy is directly affected, the required performance is even more severe.

As a method of lubricating rolling bearings used in high speed / low Λ regions such as machine tools, oil-air lubrication is often used because of problems in equipment. In particular, in machine tools that are used at high speeds and are sometimes used in high temperature environments, oil-air lubrication is often adopted as a more reliable lubrication method.

Conventionally, rolling bearings used in such a high speed / low Λ region have been made to have a long life by adjusting the supply amount of lubricating oil, and the rolling bearing itself is manufactured by the same method as a usual one. Met. The above-mentioned oil film parameter is a calculation index indicating the lubrication state, and the minimum oil film thickness h _min between the raceway surface and the rolling surface of the rolling element and the rolling surface and the rolling surface of the rolling element Surface roughness σ ₁ , σ ₂ (root mean square surface roughness)
Is calculated from the following equation. Oil film parameter Λ = h _min / (σ ₁ ² + σ ₂ ² ) ^1/2

[0008]

Rolling bearings used in compressor devices for air conditioners, etc. are used at high speeds and in some cases in high temperature environments.
Lubricating with refrigerating machine oil containing a refrigerant may not sufficiently form a lubricating oil film. In addition, the above-described lubricant supply method has a problem that the supply amount of the lubricant is likely to be insufficient.

Further, in a rolling bearing for a machine tool used in a high temperature / low Λ region and in some cases in a high temperature environment, a lubricating oil film is not sufficiently formed due to insufficient supply of lubricating oil or temperature increase due to high speed rotation. There are cases. When the lubrication is insufficient in this way, the presence of foreign matter such as abrasive grains on the raceway surface of the bearing ring or the rolling surface of the rolling element that constitutes the rolling bearing causes There was a risk of peeling wear and peeling on the rolling surface.

On the other hand, in a rolling bearing used for the main shaft of a machine tool, etc., when foreign matter enters between the bearing ring and the rolling element and is bitten, an indentation is generated in the running portion of the bearing ring, resulting in an indentation edge. There is a problem in that the surface concentration type early peeling starting from the indentation occurs due to the stress concentration, and the life is shortened. Further, among the above-mentioned foreign matters, if a hard foreign matter such as abrasive grains is caught between the bearing ring and the rolling element, the foreign matter may slip into the running portion of the bearing ring and be fixed. When the rolling element rolls along the running portion of the track in such a state, band-shaped localized indentation concentration (band wear) occurs on the rolling element. The rolling element having such band-shaped indentation concentration rotates inside the bearing while further changing its rotation axis, and therefore seizure and acoustic failure due to poor lubrication of the bearing are likely to occur.

Therefore, the present invention solves the problems of the conventional rolling bearing as described above, and has a long life even under the severe lubrication conditions such as refrigerating machine oil containing a refrigerant and high speed / low Λ region. An object is to provide a bearing. Another object is to provide a rolling bearing with long life and high accuracy even when used in a machine tool under high speed rotation and high load. Further, it is also an object to provide a method for manufacturing a rolling bearing as described above.

[0012]

In order to solve the above-mentioned problems, the present invention has the following constitution. That is, the rolling shaft according to the first aspect of the present invention is rotatably disposed between the outer ring and the inner ring, and the outer ring and the inner ring formed by subjecting the plate material to the surface processing treatment instead of the punching grinding processing. A plurality of rolling elements, and a rolling bearing in which a refrigerating machine oil containing a refrigerant is filled in a void portion formed between the outer ring and the inner ring and in which the rolling elements are provided, It is characterized in that no foreign matter having an average diameter of more than 3 μm exists on the raceways of the outer ring and the inner ring.

According to a second aspect of the present invention, in the rolling bearing according to the first aspect, there is no foreign matter having an average diameter exceeding 3 μm on the rolling surface of the rolling element. Is characterized by. The rolling bearing having such a configuration has a long life even when used under severe lubrication conditions such as lubrication with refrigerating machine oil containing a refrigerant.

If foreign matter having an average diameter of more than 3 μm is present on the raceways of the inner and outer races, abnormal rolling wear occurs on the rolling elements when the rolling elements are rotated in a depleted lubrication state, leading to separation. Therefore, the life of the rolling bearing becomes insufficient.
This is because foreign matter having an average diameter of more than 3 μm attached to the raceway surface scrapes the rolling elements. Such a phenomenon tends to occur when the thickness of the lubricating oil film is thin, and when the thickness of the lubricating oil film is thin, the above-mentioned peeling wear also occurs and the life is further shortened.
If the foreign matter does not exist or if it has an average diameter of 3 μm or less, the occurrence of such a phenomenon is suppressed,
The rolling bearing has a long life. The average diameter means the average value of the major axis and the minor axis of the foreign matter.

The present inventors have confirmed that such foreign matter adheres to the raceway surface during surface processing such as barrel processing. Furthermore, it was found that the size and amount of foreign matter adhering to the raceway surface differ depending on the size of the abrasive grains used for barrel processing. Therefore, by reducing the size of the abrasive grains used during barrel processing, it is possible to reduce the size of the remaining abrasive grains (adhering foreign matter). However, if it is made too small, there is a weak point that the time required for barrel processing becomes long.

Therefore, a shot peening treatment using steel beads containing no abrasive grains such as alumina is performed.
More preferably, it is applied as a surface treatment. Then, almost no foreign matter remains on the raceway surface. On the other hand, the foreign matter existing on the rolling surface of the rolling element does not directly wear the rolling element itself, but when the foreign matter falls off, it adheres to the raceway surface or floats on the rolling surface. If so, there is a possibility of accelerating the wear of the rolling elements, so it is preferable that no foreign matter having an average diameter of more than 3 μm is present on the rolling surface.

Further, a rolling shaft according to a fifth aspect of the present invention includes an outer ring, an inner ring, and a plurality of rolling elements rotatably arranged between the outer ring and the inner ring.
A rolling bearing used in a machine tool, characterized in that no foreign matter having an average diameter of more than 3 μm is present on the raceways of the outer ring and the inner ring. Further, a rolling shaft according to a seventh aspect of the present invention is characterized in that, in the rolling bearing according to the fifth aspect, it is oil-lubricated and is used at a high speed and under a condition that an oil film parameter is small.

The rolling bearing having such a structure has a long life and high accuracy even when used in a machine tool under high speed rotation and high load. Further, it has a long life even when used under severe lubrication conditions such as high speed and low Λ region. When foreign matter having an average diameter of more than 3 μm is present on the raceways provided on the outer ring and the inner ring, the foreign matter is caught between the raceway and the rolling elements to generate indentations on the raceways, and thus the rolling bearing. Life and accuracy are insufficient. If the foreign matter does not exist or if it has an average diameter of 3 μm or less, the rolling bearing has a long life and high accuracy. In order to make the rolling bearing have a longer life and higher accuracy, the average diameter of the foreign matter existing on the raceway surface is more preferably 2 μm or less, further preferably 1 μm or less. The average diameter means the average value of the major axis and the minor axis of the foreign matter, as in the case described above.

As a method for preventing foreign matter having an average diameter of more than 3 μm from existing on the raceway surface, a method of subjecting the raceway surface to a surface treatment is preferable. By this process, the foreign matter existing on the raceway surface can be removed. Examples of the surface treatment include barrel treatment and shot peening treatment, and the foreign matter can be removed by performing one or both of them.

However, in the case of the rolling bearing according to claim 7 which is used under severe lubrication conditions such as a high speed / low Λ region, at least one of cross treatment, ultrasonic cleaning treatment and brush cleaning treatment is applied to the surface. It is preferably applied as a processing treatment. The inventors of the present invention first examined the life of rolling bearings lubricated with refrigerating machine oil in which a refrigerant was melted, and rolling bearings used under severe lubrication conditions such as high speed and low Λ range. The forms of peeling wear and peeling that occurred on the rolling bearing were observed. As a result, traces of foreign matter such as abrasion powder caught on the raceways of the inner and outer races and the rolling surfaces of the rolling elements where the peeling occurred as described above, and wear patterns due to minute foreign matter were observed.
When observing the bite marks and wear patterns in more detail,
It was observed that the same scars remained repeatedly.

From these results, it was considered that foreign matter was mixed in as a cause of the peeling described above. That is,
As the foreign matter is fixed on the raceways of the inner and outer rings and the rolling elements are repeatedly scratched, the roughness of the rolling surface of the rolling elements increases, and eventually abnormal wear or peeling occurs, leading to peeling. It is estimated to be. Abnormal wear is a phenomenon in which foreign matter remaining on the raceways of the inner ring and the outer ring wears the rolling elements, and peeling is a phenomenon in which the rolling elements slip due to insufficient lubrication.

Therefore, a rolling bearing lubricated with refrigerating machine oil in which a refrigerant is melted or a rolling bearing used under severe lubrication conditions such as a high speed / low Λ region are rotated, and relatively good before the peeling occurs. In this state, the raceway surface and rolling surface of the rolling bearing were observed. As a result, even in such fatigue initial state, the inner ring, the outer ring,
And, it was confirmed that the rolling elements were repeatedly scratched as described above. Furthermore, fixed foreign matter was confirmed on the raceways of the inner and outer rings. When the state and composition of the fixed foreign matter were investigated, it was found to be a ceramic composition such as alumina, which is a non-metal composition.

Furthermore, when observing the raceway surface and rolling surface of an unused rolling bearing, the presence of foreign matter of ceramic component or metallic material was confirmed, and when the rolling bearing was completed, the raceway surface and rolling surface were already formed. It was found that foreign matter may be attached to the surface. And such foreign matter is
It is considered that when the raceway surface of the rolling bearing is finished by a surface processing treatment using abrasive grains such as barrel treatment, the abrasive grains remain on the raceway surface. Further, it is considered that the abrasive grains remained on the rolling surface when the rolling surface was finished by a surface treatment using abrasive grains after the grinding.

From the above, in the rolling bearing which is lubricated with the refrigerating machine oil in which the refrigerant is melted, or the rolling bearing which is used under severe lubrication conditions such as high speed and low Λ region, the abrasive grain such as barrel treatment is used. In the finishing process by the surface treatment, the slight abrasive grains remaining on the raceways and rolling surfaces of the rolling bearing may cause the abnormal wear and the peeling, which may significantly reduce the life of the rolling bearing. I understood.

In order to remove the foreign matter existing on the raceway surface and the rolling surface, the present inventors have carried out surface processing such as barrel processing, shot peening processing, cloth processing, ultrasonic cleaning processing and brush cleaning processing. It has been found that applying is effective.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a rolling bearing according to the present invention will be described in detail with reference to the drawings. [First Embodiment] A rolling bearing according to a first embodiment of the present invention, that is, a rolling bearing lubricated with refrigerating machine oil containing a refrigerant will be described.

FIG. 1 is a vertical sectional view showing the structure of a thrust needle bearing which is a first embodiment of the rolling bearing according to the present invention. The thrust needle bearing includes an outer ring 1 fixed to a housing (not shown), an inner ring 2 fixed to a shaft (not shown), and a plurality of rolling elements 3 rotatably arranged between the wheels 1 and 2. , A plurality of rolling elements 3 on both wheels 1,2
And a refrigerating machine oil (PAG) 5 which is filled between the two wheels 1 and 2 and which is filled in a space in which the rolling element 3 is provided. In addition, this refrigerator oil 5
Contains CFC which is a refrigerant.

Since the raceway surfaces 1a and 2a of the two wheels 1 and 2 and the rolling surface 3a of the rolling element 3 are subjected to surface processing such as barrel processing and shot peening processing, the raceway surfaces 1a and 2a. No foreign matter such as abrasive grains having an average diameter of more than 3 μm was found on the top and the rolling surface 3a. Therefore, such a thrust needle bearing can be suitably used for a compressor device of an air conditioner and the like.

More specifically, in a rolling bearing used in a compressor device of an air conditioner, the amount of lubricant (refrigerating machine oil) initially enclosed in the compressor device is very small, and Since a lubricant method in which the lubricant is agitated and splashed is adopted, the supply amount of the lubricant is likely to be insufficient and the lubrication conditions are severe. Further, since CFC used as a refrigerant is dissolved in the lubricant, the kinematic viscosity of the lubricant is extremely lowered, and it is difficult to form an oil film, and the lubrication conditions are further severed.

When the lubrication is insufficient in this way,
The presence of foreign matter such as abrasive grains on the raceway surface of the bearing ring or the rolling surface of the rolling element that constitutes the rolling bearing may cause peeling wear or peeling on the rolling surface, which may lead to peeling. is there. However, since the above-mentioned thrust needle bearing is subjected to a surface treatment such as a barrel treatment using abrasive grains of a predetermined size and a shot peening treatment without using abrasive grains, the surface treatment on the raceways 1a, 2a and There is no foreign matter such as abrasive grains having an average diameter of more than 3 μm on the rolling surface 3a. Therefore, the thrust needle bearing has a long life even under the severe lubrication conditions as described above.

The outer ring 1 and the inner ring 2 are made of JIS chrome molybdenum steel SCM415. The manufacturing method is as follows. After punching the outer ring 1 and the inner ring 2 from the steel plate of the above material, carbonitriding treatment (830 to 850 ° C.) and tempering (150 to 200 ° C.) are performed, and the raceway surfaces 1 a and 2 a are barrel treated, Surface treatment such as shot peening is performed. In normal bearings, grinding is applied, but in this thrust needle bearing,
Instead of the grinding process, the above-mentioned surface processing treatment is applied.

The rolling element 3 is JIS bearing steel SUJ2.
It is composed of. The manufacturing method is as follows. After cutting the rolling elements 3 from the wire material of the above-mentioned material, quenching (830 to 850
℃) and tempering (160-200 ℃), rolling surface 3
The surface a is subjected to polishing, barrel treatment, shot peening treatment, and the like. [Example 1] In a bearing similar to such a thrust needle bearing,
The inner and outer races and the rolling elements were subjected to surface treatment under various conditions, and their life tests were conducted.

As this surface processing treatment, barrel treatment using abrasive grains of a predetermined size and shot peening treatment not using abrasive grains were performed. Barrel processing has three conditions,
The shot peening treatment was performed under two conditions, and five types of inner and outer races and rolling elements were produced respectively. Then, by combining these inner and outer rings and rolling elements in various ways, 25 kinds of test bearings having different surface processing conditions (see Tables 1 and 2 described later)
No. described in No. 1-No. 25 bearings) were manufactured.

The abrasive grains used in the barrel treatment were limited to the alumina-based abrasive grains used in the processing of the bearing. And it processed using the abrasive grain (mesh No. 200-8000) of various sizes, and manufactured the test bearing. The alumina-based abrasive grains (chips) used were all chips containing fused alumina as a main component. Alundum # 200 (for medium grinding stone), alumina # 1000 to 2000 (for gloss stone), alumina # 6000. ~ 8000 (in the case of ultra-glossy stone) (all manufactured by Nippon Diamond Industrial Co., Ltd.).

Since the size of the abrasive grains used in the manufacture of the bearing varies depending on the processing steps, the three types of chips are used for barrel processing as described above in order to determine which process the abrasive particles are used for. did. The treatment time was set to 60 minutes in each case so that only the effect of the size of the abrasive grains on the life could be confirmed.

Next, the shot peening process will be described. The shot peening treatment is a kind of cold working and is a treatment in which a large number of ferrous or non-ferrous metal spheres collide with the metal surface at high speed. This ball is called a shot. Generally, the shot is harder than the material to be treated, so when the shot collides with the surface of the material at high speed, the surface of the material to be treated is dented and the surface is covered with innumerable recesses to give a pear-skin pattern. . Then, the hardness of the surface of the material to be treated increases and the fatigue strength increases.

In the present embodiment, shot peening treatment was performed using high carbon cast steel shot produced by spraying molten steel. Then, the conditions were set to two conditions of treatment time of 30 minutes and 120 minutes, other conditions such as the type of shot material were made constant, and only the influence of the treatment time on the service life could be confirmed. The test thrust needle bearing manufactured in this manner was tested using a thrust type bearing life tester manufactured by NSK Ltd. for a test load of P / C = 0.3 and a bearing rotational speed of 5000 mi.
The basic rated life (10 ⁶ rotations) L ₁₀ under clean lubrication was measured under the condition of n ⁻¹ .

As the lubricant, white kerosene was mixed with the refrigerating machine oil in order to reproduce the state in which the refrigerant (freon) was dissolved in the refrigerating machine oil (PAG) used in the compressor device of the air conditioner and the viscosity was lowered. What was used (mixing ratio was refrigerator oil: white kerosene = 7: 3). The life test was conducted under atmospheric pressure. Further, assuming that the temperature of the lubricant increases and the formation of the oil film becomes insufficient, the evaluation was performed at a test temperature of 100 to 120 ° C. under severe lubrication conditions.

Tables 1 and 2 show the details of the surface treatment applied to each bearing (inner and outer rings and rolling elements), the compressive stress σ _R remaining on the raceways and rolling surfaces, and the raceways and rolling surfaces. The number and the average diameter of the foreign substances present in are shown, and the test results (bearing life) are also shown.

[0040]

[Table 1]

[0041]

[Table 2]

The number and size of foreign matters existing on the raceway surface and rolling surface were measured by observing the raceway surface and rolling surface with an electron microscope (made by JEOL Ltd.). The measuring method is as follows. Disassemble the bearing and divide it into inner ring, outer ring, rolling elements, and cage. The inner ring, the outer ring, and the rolling elements were put in a container washed with ultrapure water, isopropanol for electronic industrial materials was added, and ultrasonic waves of 38 kHz were applied for washing for 10 minutes. The washed member was observed with a scanning electron microscope at 1000 times, and energy dispersive X-ray analysis (EDS) was performed.

The analysis conditions are an acceleration voltage of 15 kV, a sample current of 0.5 nA, and an objective diaphragm of 100 μm. Also, EDS
Is a combination of an S-UTW detector manufactured by Philips and a DX-4 analyzer. The surface analysis (color mapping) of the element to be analyzed was carried out at 512 × 400 pixels at 20 ms / pixel. After surface analysis, the size and number of target elements were measured using the particle analysis program of the same company. The test area was 0.0123 mm ² , and arbitrary 10 points were measured, and the obtained results were converted per unit area.

In the column of maximum diameter in the table, the maximum average diameter (average value of the major axis and the minor axis) of the observed foreign substances is described. Further, in the bearing lifes shown in Tables 1 and 2, ">2000" indicates that the test was aborted without peeling or wear even if the total number of tested bearings exceeded 2000 hours. ing.

As can be seen from Tables 1 and 2, No. 1
The bearings Nos. 1 to 25 showed an excellent life of 5 times or more the calculated life (185 hours). This is because the maximum diameter of the abrasive grains present on the raceways of the inner and outer rings is 3 μm or less. Among them, No. 13-15, No. 18-2
0, and No. The bearings Nos. 23 to 25 showed a very excellent life of 10 times or more the calculated life. This is because the maximum diameter of the abrasive grains present on the rolling surfaces of the rolling elements as well as the raceways of the inner and outer rings is 3 μm or less.

Regarding the processing time of the shot peening treatment, although there is no difference in the bearing life, it is desirable to treat the heat treated product for 120 minutes in consideration of the black skin residue after the shot peening treatment. On the other hand, No.
The bearings 1, 2, 6, 7 had a maximum life of abrasive grains on the raceways of the inner and outer races and on the rolling surfaces of the rolling elements larger than 3 μm, and thus had a short life equivalent to the calculated life. Also, N
o. In the bearings Nos. 3 and 8, the maximum diameter of the abrasive grains present on the rolling surface of the rolling element is as small as 3 μm, but since the maximum diameter of the abrasive grains present on the raceways of the inner and outer rings is larger than 3 μm, The moving body was worn out and the life was shortened. Furthermore, No4
In the bearings Nos. 5, 9 and 10, since the rolling elements are subjected to shot peening treatment, no abrasive grains are present on the rolling surfaces,
The life is governed by the abrasive grains that exist on the raceways of the inner and outer rings,
The life could only be improved to about twice the calculated life.

As described above, when the surface treatment such as the barrel treatment or the shot peening treatment using the abrasive grains of a predetermined size is performed, the grinding is performed on the raceways of the inner and outer races and the rolling surfaces of the rolling elements. It can be seen that since the adhesion of particles is prevented, abnormal wear and peeling wear are suppressed, and the bearing has a long life. [Second Embodiment] A rolling bearing according to a second embodiment of the present invention, that is, an angular contact ball bearing used for a main shaft of a machine tool will be described with reference to a vertical sectional view of FIG. In addition, in FIG. 2, the same or corresponding portions as those in FIG. 1 are designated by the same reference numerals.

This angular contact ball bearing (40BNC10
T) is an outer ring 1 fixed to a housing (not shown),
An inner ring 2 fixed to a shaft (not shown), and both wheels 1 and 2
It is provided with a plurality of rolling elements 3 arranged between the wheels 1 and 2 and a cage 4 for holding the plurality of rolling elements 3 between the wheels 1 and 2. Both wheels 1, 2 and rolling element 3 are JIS bearing steel SU
It is made of J2 material and is quenched at 830-850 ° C. Further, both wheels 1 and 2 are subjected to high temperature tempering at 230 to 260 ° C. as a dimension stabilizing treatment, and the rolling elements 3 are
Normal tempering at 60 to 200 ° C is applied.

The raceways 1a and 2a of the two wheels 1 and 2 are finished by ordinary grinding.
However, since the abrasive grains forming the processing grindstone used during grinding may remain on the raceways 1a, 2a,
Surface treatment (barrel treatment and shot peening treatment) is performed as a post-treatment. By such surface processing, no foreign matter such as abrasive grains having an average diameter of more than 3 μm was confirmed on the raceways 1a and 2a. Therefore, such an angular contact ball bearing can be suitably used for a spindle of a machine tool or the like, and has a long life and high accuracy even when used under high speed rotation and high load.

Example 2 A bearing similar to the above angular ball bearing was prepared by subjecting the raceways of the inner and outer races to surface treatment under various conditions, and a life test was conducted. As the surface processing treatment, barrel treatment using abrasive grains of a predetermined size and shot peening treatment not using abrasive grains were performed. The barrel treatment was carried out under three conditions and the shot peening treatment was carried out under five conditions to produce 17 kinds of inner and outer rings. Then, using these inner and outer rings, 17 kinds of test bearings having different surface processing conditions (bearings No. 101 to No. 117 described in Table 3 described later)
Was manufactured.

The abrasive grains used in the barrel treatment are the same as in the case of Example 1 described above. The processing time was set to 60 minutes in each case so that only the effect of the size of the abrasive grains on the life could be confirmed. The shot peening process is also the same as in the case of the above-described first embodiment. Processing time is 10, 20, 3
The conditions were 0, 60, and 5/120, and other conditions such as the type of shot material were constant, so that only the influence of the treatment time on the life could be confirmed.

The test angular contact ball bearing manufactured in this manner was subjected to a basic rating life (10 ⁶ revolutions) L ₁₀ under clean lubrication under the following conditions using a high speed bearing life tester manufactured by NSK Ltd. It was measured. Assuming a machine tool bearing, the rotation speed was set to high speed and the lubricating oil had low viscosity as described below. Preload: 1.2 kN Bearing rotation speed: 30000 min ⁻¹ Test temperature: 80 to 90 ° C. Lubricating oil: Nisseki Mitsubishi Super Malpass # 10
(Kinematic viscosity at 40 ° C. = 10 mm ² / s) Table 3 shows the contents of the surface treatment applied to the inner and outer rings of each bearing,
The number and the average diameter of foreign substances existing on the raceway surface are shown, and the test results (bearing life) are also shown.

[0053]

[Table 3]

The number and size of foreign substances existing on the orbital surface were measured by observing the orbital surface with an electron microscope (manufactured by JEOL Ltd.). The measuring method is the same as in the case of the above-mentioned first embodiment. In the column of maximum diameter in the table, the maximum average diameter (average value of the major axis and the minor axis) of the observed foreign substances is described.

Further, in the bearing life shown in Table 3, ">97"
Those marked with "0" indicate that the test was aborted without any peeling or wear even after the total number of tested bearings exceeded the calculated life of 970 hours. As can be seen from Table 3, there is no foreign matter having an average diameter of more than 3 μm on the raceways of the inner and outer rings (No. 101 to 108).
Bearing) has an excellent bearing life, and in particular, a bearing having no foreign matter on the raceways of the inner and outer rings (bearing No. 108) and a bearing having a maximum diameter of 3 μm or less (No. 1).
Bearings 01 to 107) had a very long bearing life. On the other hand, bearings (Nos. 109 to 117) in which foreign matters having an average diameter of more than 3 μm exist on the raceways of the inner and outer rings.
Bearing) had an insufficient bearing life.

It can be seen that the shot peening treatment is effective in removing foreign matters existing on the raceway surface, and the longer the treatment time, the smaller the number of foreign matters and the longer the bearing life. However, in order to obtain an excellent bearing life, it is necessary to perform the shot peening treatment for a sufficient time according to the number and diameter of the foreign matters existing on the raceway surface before the shot peening treatment. For example, No. The bearing No. 110 has been subjected to shot peening treatment for 20 minutes, and its effect can be seen, but the treatment time is insufficient to obtain an excellent bearing life.

Further, in No. 1 which is not surface-treated.
As can be seen from the comparison with the bearing of No. 109, the number of foreign particles tends to increase when the barrel treatment is performed because the abrasive grains used for the barrel treatment adhere to the raceway surface. Then, when a gloss stone or a medium grinding stone is used as the abrasive grains (No. 111, 1
(No. 112, 113, 115-1), the bearing life of the bearing 14 is short because the abrasive grains are large, and the treatment time is short even if the shot peening treatment is performed after the barrel treatment (No. 112, 113, 115-1).
No. 17 bearing), the abrasive grains could not be sufficiently removed, and the bearing life was short.

However, when super-glossy stones are used as the abrasive grains (bearing Nos. 104 to 108), the abrasive grains are small, and even if they adhere to the raceway surface, they do not become foreign matter exceeding 3 μm, so the bearing life is long. Was excellent. As described above, if at least one of the barrel treatment using the abrasive grains of a predetermined size and the shot peening treatment for a sufficient time is performed as the surface treatment, peeling wear or peeling peeling can be prevented in the rolling bearing for machine tools. It can be understood that the rolling bearing has a long life because foreign matters such as abrasive grains that cause acceleration are prevented from remaining on the raceways of the inner and outer rings.

[Third Embodiment] A third embodiment of the present invention is an angular ball bearing used for a spindle of a machine tool, which is an angular ball bearing different from the second embodiment. However, since the configuration is almost the same as that of the angular ball bearing of the second embodiment, only different parts will be described, and in that case, description will be made with reference to FIG. 2.

The angular contact ball bearing of the third embodiment has a nominal number 7205, and both wheels 1 and 2 and the rolling element 3 are made of the same JIS bearing steel SUJ2 material as in the second embodiment, and are subjected to the same heat treatment. There is. The raceways 1a and 2a of the two wheels 1 and 2 are finished by ordinary grinding. However, it is assumed that the processing grindstone used during grinding is formed of alumina-based abrasive grains used during bearing processing, and the grain size of the abrasive grains is 3.2 to 4.2 μm.
(Mesh No. 6000 to 8000).

Since the abrasive grains forming the processing grindstone may remain on the raceway surfaces 1a, 2a after the grinding process,
Surface treatment (at least one of cloth treatment, ultrasonic cleaning treatment, and brush cleaning treatment) is performed as a post-treatment. By such surface processing, raceway surface 1
No foreign matter such as abrasive grains having an average diameter of more than 3 μm was observed on a and 2a. Therefore, such an angular contact ball bearing can be suitably used for the spindle of machine tools, etc., and has a long life and high accuracy even when used at high speed, under high load, under a thin oil film (low Λ range). is there.

Example 3 A bearing similar to the above angular ball bearing was prepared by subjecting the raceways of the inner and outer races to surface treatment under various conditions, and a life test was conducted. At least one of a cloth treatment, an ultrasonic cleaning treatment, and a brush cleaning treatment was performed as the surface processing treatment. The cloth treatment was performed under five conditions, and the ultrasonic cleaning treatment and the brush cleaning treatment were each performed under three conditions, and a total of 26 types of inner and outer rings were produced. Then, using these inner and outer rings, 26 kinds of test bearings having different surface processing conditions (No. 201 described in Tables 5 and 6 described later) were used.
~ No. 226 bearings) were manufactured.

Here, the cloth treatment is a treatment of winding a cloth (cloth) made of a strong synthetic fiber around a wooden rod and rubbing the raceway surface. The influence of the treatment time on the life was confirmed under the five treatment conditions of 0, 10, 30, 60, and 120 seconds. The cloth used was Savina Minimax clean room dressing cloth manufactured by Kanebo Synthetic Fibers Co., Ltd.

The ultrasonic cleaning treatment is an ultrasonic cleaning machine (manufactured by Kaijo Co., Ltd., conditions: 200 kHz, 600).
In step W), ultrasonic cleaning of the inner and outer rings is performed. The effect of the treatment time on the service life was confirmed under three treatment conditions of 0, 300, and 600 seconds. Further, the brush cleaning process is a process of rubbing the raceway surface with a durable nylon brush. The effect of the treatment time on the life was confirmed under the three treatment conditions of 0, 100, and 300 seconds.

For the test angular contact ball bearing thus manufactured, a basic rating life (10 ⁶ revolutions) L ₁₀ under clean lubrication was used under the following conditions using a high speed bearing life tester manufactured by NSK Ltd. It was measured. Test load: P / C = 0.166 (P is a dynamic equivalent load of 2450N, C is a basic dynamic load rating of 14798N
Bearing rotation speed: 15000min ^-1 Roughness of inner ring raceway surface: 0.05 μmRa Roughness of rolling surface of rolling element: 0.007 μmRa Lubrication method: Oil air lubrication (lubricant supply amount is 2
(ml / min) Incidentally, assuming the bearing for machine tools, the rotation speed was set to the high speed rotation as described above. Also, in order to reproduce the severe lubrication condition that the oil film thickness is small and low Λ, Super Malpass # 10 (kinematic viscosity at 40 ° C = 10 mm ² / s) made by Mitsubishi Nisseki Co., Ltd. was used as the lubricating oil at the test temperature. Is 100-12
It was set to 0 ° C.

For reference, Table 4 shows the kinematic viscosity of the lubricating oil at each temperature, the minimum oil film thickness and the oil film parameter Λ in the angular ball bearing.

[0067]

[Table 4]

Tables 5 and 6 show the contents of the surface processing applied to the inner and outer races of each bearing, the maximum diameter of foreign matter existing on the raceway surface, and the test results (bearing life). A graph summarizing these results is shown in FIG. This graph shows the correlation between the maximum diameter of foreign matter on the raceway surface and the bearing life. If the maximum diameter of foreign matter exceeds 3 μm, plot it by ●, otherwise plot it by ○. I am doing it.

[0069]

[Table 5]

[0070]

[Table 6]

The maximum diameter of foreign matter existing on the raceway surface is 10 arbitrary points on the raceway surface (the visual field is 40 μm in length × 50 in width).
(μm) was observed by an electron microscope (manufactured by JEOL Ltd.) at a magnification of 2000 times. In the columns of maximum diameters in Tables 5 and 6, the maximum average diameter (average value of the long diameter and the short diameter) of the observed foreign matters is described. In addition, in the bearing life shown in Tables 5 and 6, "1250 or more" indicates that all tested bearings have a calculated life of 5 or less.
No peeling or abrasion occurred even after the doubling of 1250 hours, indicating that the test was terminated.

No. 205, 206, 209, 215,
From the result of the bearing 221, the maximum diameter of the foreign matter is 3 μm if the treatment is sufficiently performed until the maximum diameter of the foreign matter becomes 3 μm or less in any of the cross treatment, the ultrasonic cleaning treatment, and the brush cleaning treatment. When it exceeds (No. 201 to 20)
The bearing has a significantly longer life than that of the bearing No. 4), which is more than twice the calculated life.

Further, in the case where two or more kinds of processing among the cloth processing, the ultrasonic cleaning processing, and the brush cleaning processing are combined and performed (No. 207, 208, 210 to 214,
It can be seen that the bearings 216-220, 222-226) have a further excellent life. In particular, No. Since the maximum diameter of foreign matter in the bearings 225 and 226 is 1 μm or less,
It showed an extremely long life.

The first to third embodiments described above are examples of the present invention, and the present invention is not limited to the above embodiments. For example, in each of the above-described embodiments, the thrust needle bearing and the angular ball bearing are illustrated as the rolling bearings, but the rolling bearing of the present invention can be applied to various types of other rolling bearings. . For example, it can be applied to other types of thrust type rolling bearings such as thrust ball bearings. Further, it can be applied to other types of radial type rolling bearings such as roller bearings such as cylindrical roller bearings, self-aligning roller bearings and tapered roller bearings, and ball bearings such as deep groove ball bearings.

[0075]

As described above, the rolling bearing of the present invention is
It has a long life even under severe lubrication conditions such as lubrication with refrigerating machine oil containing a refrigerant. Further, the rolling bearing of the present invention has a long life and high accuracy even when it is used in a machine tool at high speed, under high load, and under a thin oil film. Furthermore, according to the rolling bearing manufacturing method of the present invention, the rolling bearing as described above can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing the structure of a thrust needle bearing which is a first embodiment of a rolling bearing according to the present invention.

FIG. 2 is a vertical cross-sectional view showing the structure of an angular contact ball bearing which is a second embodiment of the rolling bearing according to the present invention.

FIG. 3 is a graph showing the correlation between the maximum diameter of foreign matter existing on the raceway surface and the bearing life.

[Explanation of symbols]

1 outer ring 2 inner ring 1a, 2a orbital plane 3 rolling elements 3a Rolling surface 5 Refrigerator oil

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuo Sekino             1-5-50 Kumei, Kugenuma, Fujisawa-shi, Kanagawa             Within NSK Ltd. (72) Inventor Nobuaki Mitamura             1-5-50 Kumei, Kugenuma, Fujisawa-shi, Kanagawa             Within NSK Ltd. F term (reference) 3J101 AA02 AA32 AA42 AA52 AA62                       BA53 BA54 DA05 EA78 FA35                       GA29

Claims (8)

[Claims] 1. An outer ring and an inner ring formed by subjecting a plate material to a surface treatment instead of punching and grinding, and a plurality of rolling elements rotatably arranged between the outer ring and the inner ring. Together with the inside of the gap formed between the outer ring and the inner ring in which the rolling element is provided, a rolling bearing filled with refrigerating machine oil containing a refrigerant, on the raceways of the outer ring and the inner ring. A rolling bearing characterized by the absence of foreign matter having an average diameter of more than 3 μm. 2. The rolling bearing according to claim 1, wherein foreign matter having an average diameter of more than 3 μm does not exist on the rolling surface of the rolling element. 3. A method of manufacturing a rolling bearing according to claim 1, wherein when the rolling bearing is manufactured, the surface processing is shot peening and the surface is subjected to the processing. 4. A method of manufacturing a rolling bearing according to claim 2, wherein when the rolling bearing is manufactured, a shot peening treatment is applied to the rolling surface. 5. A rolling bearing comprising an outer ring, an inner ring, and a plurality of rolling elements rotatably arranged between the outer ring and the inner ring and used for a machine tool, comprising:
A rolling bearing characterized in that no foreign matter having an average diameter of more than 3 μm is present on the raceways of the outer ring and the inner ring. 6. A method of manufacturing a rolling bearing according to claim 5, wherein the raceway surface is subjected to a surface treatment treatment including at least one of barrel treatment and shot peening treatment. 7. The rolling bearing according to claim 5, wherein the rolling bearing is oil-lubricated and used at a high speed and a small oil film parameter. 8. When manufacturing the rolling bearing according to claim 7, at least one of a cross treatment, an ultrasonic cleaning treatment, and a brush cleaning treatment is performed on the raceways of the outer ring and the inner ring finished by grinding. A method of manufacturing a rolling bearing, which comprises subjecting a surface treatment treatment to one.