JPH03117724A - Roller bearing - Google Patents

Abstract

PURPOSE:To secure a long life for even a rough opposite surface or a finely finished surface by forming the surface of a bearing ring or the surface and that of a rolling element in the roller bearing into a randamly and finely finished surface, and restraining roughness in axial and circumferential directions of the fine rough surface in a specified range. CONSTITUTION:In a roller bearing, surfaces of the raceway surface 6 of an inner ring 2 and the bearing raceway surface 6 of a mating axis 5 are formed into a fine rough surface 7 in a randam direction. In the fine rough surface 7, when surface roughness is represented with parameter RMS by determining individual surface roughness in the axial and circumferential directions of the bearing raceway surfaces 6 and 6, the ratio RMS(L)/RMS(C) of axial direction surface roughness RMS(L) and circumferential direction surface roughness RMS(C) is made 1.0 or below, and also the parameter SK value of the surface roughness is made -1.6 or below in both directions of the axis and circumference. This causes the oil film forming ratio in the raceway surface or rolling surface to be improved, and the occurrence of peeling breakage or abrasion to be eliminated in a mating surface regardless of the degree of the surface roughness of the mating surface to obtain a long life.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a roller bearing, and more particularly to a roller bearing that exhibits a long life even when the mating surface is a rough surface or a well-finished surface.

[Conventional technology and its problems]

It is well known that the surface roughness of the raceway or rolling surface is an important factor in the life of raceway rings and rolling elements in roller bearings. Conventionally, raceways and rolling surfaces have been finished to be as smooth as possible. However, through repeated trial and error to improve the transfer fatigue life of bearings, it was discovered that a long life can be achieved without improving the finish of the raceway or transfer surface. Ta.

The raceway ring or rolling element described above has a structure in which the raceway surface or rolling surface is roughened with random scratches of RmaxO, 3 to 0.8 μm, and can exhibit the effect of long life. However, when used with a mating surface that has a good finish, the oil film may not be formed sufficiently, causing wear or peeling damage to the mating surface, and the range in which it can be used is narrow based on the finishing conditions of the mating surface. The need for improvement was found in this area.

[Purpose of the invention]

Therefore, this invention focuses on evaluating the surface roughness of the raceway surface or transfer surface of the raceway ring and rolling element not only in the axial direction but also in the rolling direction, and suppresses the surface roughness in the axial direction and the circumferential direction to a certain range. The purpose of the present invention is to provide a roller bearing with a long life, which can advantageously form an oil film and which can handle both the quality and the bad surface roughness of the mating surface.

[Means to achieve the purpose]

In order to achieve the above object, the first invention randomly forms countless independent minute concave depressions on the surface of the bearing ring in a roller bearing, and improves the surface roughness of the bearing ring surface by adjusting the surface roughness of the bearing ring surface. Find the direction and circumferential direction and set the parameter RM
When expressed as S, the ratio between the axial surface roughness RM S (L) and the circumferential surface roughness RMS (C) is RM S (L)/R
M S (C) is 1.0 or less, and the surface roughness parameter SK value is -1 in both the axial and circumferential directions.
, 6 or less.

Similarly, in a second invention, a countless number of independent minute concave depressions are randomly formed on the surface of the raceway ring and the surface of the rolling elements in a roller bearing, and the surface roughness of both surfaces is varied in the axial direction and the circular direction. When each circumferential direction is calculated and expressed by the parameter RMS, the ratio of the axial surface roughness RM S (L) and the circumferential direction surface roughness RM S (C) is RM S (L), /R
M S (C) is 1.0 or less, and the surface roughness parameter SK value is -1 in both the axial and circumferential directions.
, 6 or less.

[Effect]

One or both of the surfaces of the bearing ring and the rolling element are formed into a random micro-rough surface, the finished surface roughness parameter RMS of this micro-rough surface is determined in the axial direction (L) and the circumferential direction (C), and the ratio is calculated. RM S (L) / RM S (C) should be 1.0 or less, and the parameter SK value should be - in both the axial and circumferential directions.
1.6 or less, the rate of oil film formation on the raceway surface or transfer surface is improved, and regardless of the surface roughness of the mating surface, there will be no beeling damage or wear on the mating surface, resulting in a long life. I can do it.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

A first example of a roller bearing 1 shown in FIG. 1 has an inner ring 2 and an outer ring 3.
A second example of the roller bearing 1 shown in FIG. 2 is a needle bearing in which the cylindrical roller rolling elements 4 are incorporated into the outer ring 3. The rolling elements 4 support the mating shaft 5. Therefore, the mating shaft 5 corresponds to the inner ring 2 in the first example, and the surface of the mating shaft 5 becomes the bearing raceway surface 6.

First, in the roller bearings of the first and second examples, the surfaces of the raceway surface 6 of the inner ring 2 and the bearing raceway surface 6 of the mating shaft 5 are formed into micro-rough surfaces 7 in random directions. , when the surface roughness of this micro-rough surface 7 is determined in each of the axial and circumferential directions of the bearing raceway surface 6.6 and expressed by the parameter RMS, the axial surface roughness RM S (L) and the circumferential surface roughness are calculated. Ratio of directional surface roughness RM S (C) RM S (L)/RM S
(C) is set to 1.0 or less, for example, 0.7 to 1.0, and the surface roughness parameter SK value is set to -1.6 or less in both the axial direction and the circumferential direction.

The surface treatment for obtaining the rough surface conditions of the raceway surface 6.6 as described above can be performed by special barrel polishing to obtain the desired finished surface.

The parameter SK value refers to the skewness (SKEWNESS) of the surface roughness distribution curve, and a symmetric distribution such as a Gaussian distribution has an SK value of O, but the parameter SK value can be changed in both the circumferential and axial directions. The set value of −1.6 or less is a range in which the shape and distribution of surface recesses are favorable for oil film formation.

Further, in the roller bearings of the first and second examples, the second invention provides that the surfaces of the raceway surface 6 of the inner ring 2 and the bearing raceway surface 6 of the mating shaft 5 are made into the micro-rough surface 7 shown in the first invention. At the same time, the surface of the rolling element 4.4 is also processed into the same micro-rough surface 7 as described above.

Next, a description will be given of the results of a life test conducted on a plurality of types of two-dollar bearings in which the raceway surface of the inner ring and the rolling surface of the rolling elements were subjected to surface treatments with different finishes.

As shown in Fig. 3, the needle bearing used in the life test had an outer diameter of -38m11. Inner diameter dr = 2811ffl
, the diameter D of the rolling element 4 is 5 m, the length is -13 m, and 14
This is a bearing with a cage 8 that uses real rolling elements.

The test bearings were conventional bearing A, which had an inner ring with a ground finish and rolling elements with a standard finish, bearing B of the first invention, which had a micro-rough surface machined on the raceway surface of the inner ring and used a standard finish for the rolling elements, and the inner ring raceway. Three types of bearings were manufactured, including the bearing C of the second invention in which both the surface and the rolling surface of the rolling elements were processed into a micro-rough surface.

For each test bearing, the finished surface condition of the standard roller is shown in FIG. 4, and the finished surface condition of the inner ring raceway surface and the rolling surface of the rolling elements subjected to micro-roughening is shown in FIG. 5 for comparison.

The test equipment used was a radial load tester 11 as shown schematically in Fig. 6. Test bearings A to C were installed on both sides of the rotating shaft 12, and the test was performed by applying rotation and load. It is something to do.

In addition, the inner ring grinding finished surface has an Rmax of 0.4 to 4 μm. In addition, the micro-rough surfaces of bearings B and C have an Rtaax of 2.5p.
m and 4 lines. The outer race (outer ring) has a ground finish Rmax of 1.6-, which is common in all cases.

Moreover, the test conditions are as follows.

Bearing radial load 1465kgf rotation speed
305 Orpm lubricant Turbine oil The test results conducted on each test bearing A, B, and C under the above conditions are shown in FIGS. 7 and 8.

FIG. 7 shows the life data of the rolling elements in each of the test bearings A, B, and C, and FIG. 8 shows the results of the inner ring surface roughness and durability life of each test bearing.

As is clear from the above test results, the test bearings B and C of the present invention all exhibited longer lifespans than the conventional test bearing A.

That is, compared to the conventional test bearing A, the test bearing B of the present invention
The life of test bearing C is about 7 times longer.

Further, when transferring between the finished surface and the rough surface, bealling damage is often observed on the finished surface side, but this was not observed in test bearings B and C of the present invention.

Figures 9 and 10 show the SK values of each test bearing A, B, and C.
The results of determining RMS L/C and life (L+) are shown.

As shown in FIG. 9, the test bearing B5C with an SK value of -1.6 or less showed a long life.

Further, it was found that even when the axial roughness RMS (L/C) was 1.0 in the special barrel polishing process as shown in FIG. 10, the product had a long life.

It has also been found that the RMS (L/C) value alone is insufficient to evaluate the rolling elements of long-life bearings.

Next, Table 1 shows the calculated values for the oil film parameters based on Grubin's equation for the combination of test bearings A and B with standard rollers under the above test conditions.

As a result of calculation, the oil film parameter A is greatly influenced by the roughness of the mating shaft surface, and when Rvaax is 2.5, bearing A is 1.1.
5. Bearing B is 0.78.

In general, there is a relationship between oil film parameters and oil film formation rate as shown in Figure 11, and it is said that the larger the oil film parameter is, the better from the viewpoint of service life. It cannot be explained by just that.

To check the oil film formation status and peeling resistance on the finished inner ring surface, test pieces with the same surface condition as the inventive test bearing B and the conventional test bearing A were tested under free rolling conditions using a two-cylindrical testing machine. An accelerated beer test was conducted using the same.

The status of oil film formation was confirmed using a direct current method.

Test conditions Maximum contact pressure 227kgf/mm” Peripheral speed 4.2m/sec (2000rpm+)
Lubricant Turbine oil Repeated loading frequency 4.8 x 10' (4 hr) The oil film formation rate in this test is as shown in Figures 12 and 13, and the oil film formation rate on the finished surface of the test bearing B of the present invention is: Compared to conventional test bearing A, the oil film formation rate was improved by about 20% at the start of operation.

Furthermore, it was confirmed that an oil film was almost completely formed when the number of repeated loads was 1.2×10′.

Further, on the finished surface of the conventional test bearing A, many occurrences and progress of peeling of about 0.1 mm in length were observed, whereas on the finished surface of the present invention test bearing B, no damage was observed.

〔effect〕

As described above, according to the present invention, the surface of the bearing ring in a roller bearing or this surface and the surface of the rolling element are formed into random micro-rough surfaces, and the roughness of the micro-rough surfaces in the axial direction and circumferential direction is Since it is kept within a certain range, it is advantageous for the formation of an oil film on the raceway ring and rolling element, and it is possible to obtain a long life even when the mating surface is rough or well-finished, and prevents wear and peeling of the mating surface. The effect is that there is no damage.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a first example of a roller bearing, Fig. 2 is a sectional view showing a second example of a roller bearing, Fig. 3 is a sectional view of a needle bearing used in the life test, and Fig. 4 and Fig. 5 are schematic diagrams showing the finished surface condition of rolling elements in the test bearing, Fig. 6 is a schematic diagram of the test equipment, Fig. 7 and Fig. 8 are graphs showing the results of the rolling fatigue life test, and Fig. 8 is a graph showing the results of the rolling fatigue life test. Figure 9 is a graph showing the relationship between SK value and service life, Figure 10 is a graph showing the relationship between RMS (L/C) value and service life, Figure 11 is a relationship diagram showing oil film parameters and oil film formation rate, and Figure 12 is a graph showing the relationship between oil film parameters and oil film formation rate. and FIG. 13 are graphs showing the oil film formation rate. 1...Roller bearing, 2...Inner ring, 3...Outer ring, 4...Rolling element, 5...Mating shaft, 6. ...Bearing raceway surface, 7...Micro-rough surface.

Claims (2)

[Claims] (1) A countless number of independent minute concave depressions are randomly formed on the surface of the bearing ring in a roller bearing, and the surface roughness of the bearing ring surface is determined in both the axial direction and the circumferential direction using the parameter RMS. When displayed, the axial surface roughness RMS (L
) and the circumferential surface roughness RMS(C) RMS(L)/
RMS (C) is 1.0 or less, and the surface roughness parameter SK value is -1.0 in both the axial and circumferential directions.
Roller bearings designed to be 6 or less. (2) A countless number of independent minute concave depressions are randomly formed on the surface of the bearing ring and the surface of the rolling elements in a roller bearing, and the surface roughness of both surfaces is adjusted in both the axial direction and the circumferential direction. When calculated and expressed in the parameter RMS, the axial surface roughness RMS (L) and the circumferential surface roughness RMS (C)
A roller bearing in which the ratio RMS(L)/RMS(C) is 1.0 or less, and the surface roughness parameter SK value is -1.6 or less in both the axial and circumferential directions. .