JP2957737B2 - Thrust rolling bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust rolling bearing, and more particularly to a thrust rolling bearing in which a bearing ring which receives a thrust load on its surface has a long life.

[0002]

2. Description of the Related Art FIG. 1 shows a hydraulic pump as an example of use of a thrust rolling bearing. A swash plate 3 is provided on a drive shaft 2 supported by a casing 1 and is held by a cylinder block 4 so as to be movable in the axial direction. The swash plate 3 is brought into contact with the swash plate 3 by pressing the plunger 5, and the pressure fluid is discharged from the suction port 7 to the discharge port 8 by the pump action of the plunger 5 to which the reciprocating motion is given by the rotation of the swash plate 3. , And a thrust rolling bearing 9 is incorporated in the swash plate 3.

As shown in FIG. 2, a thrust rolling bearing 9 of the swash plate 3 has a roller or steel ball rolling element 12 between two races 10 and 11 using a flat ring. The thrust rolling bearings 9 are formed in a circle at regular intervals, and the thrust rolling bearings 9 are held in an inclined arrangement by abutting the housing 14 of the swash plate 3 as a fixing member to which one of the bearing rings 10 is attached. The tip of the plunger 5 abuts on the outer surface of the other race 11, and this race 11 is
The surface in contact with 2 is the rolling raceway surface 11a, and the surface on the opposite side is the contact surface of the plunger 5.

Since the surface of the race 11 in the conventional thrust rolling bearing 9 is finished to a smooth surface, the thrust load between the rolling element 12 and the race 11a of the race 11 becomes large. Under severe conditions, oil film formation becomes insufficient, and the race 11 and the rolling elements 12
There is a possibility that the oil film is cut at the contact portion of the bearing ring 11 and the above-mentioned contact portion of the bearing ring 11 is gallinged early.

SUMMARY OF THE INVENTION It is an object of the present invention to sufficiently form an oil film on a raceway surface which comes into contact with a thrust load, improve lubrication, prevent early galling, and improve durability to extend the life. An object of the present invention is to provide a thrust rolling bearing capable of achieving the following.

Further, when the bearing is used as shown in FIG. 2, there is a concern that an oil film may not be sufficiently formed at a portion where the surface of the bearing ring opposite to the raceway surface contacts the plunger.
An object of the present invention is to provide a thrust rolling bearing capable of sufficiently forming an oil film at the contact portion.

[0007]

According to a first aspect of the present invention, there is provided a fixing member having a rolling element having a bearing disposed between two raceway surfaces and mounting the bearing. The surface of the orbital ring that rotates relative to the surface is provided with innumerable random indentations at random, and the average area of these indentations is reduced except for the equivalent circular diameter of 3 μmφ or less.
150 μm ² , the ratio of minute cavities to the surface is 1
The configuration adopting 0 to 40% is adopted.

[0008]

[Action] An infinite number of independent minute recesses are randomly provided on a raceway surface of a thrust rolling bearing where rolling contact of a race ring is made, and an average area of the minute recesses is calculated as an equivalent circular diameter of 3.
35 to 150 μm ² when arranged except for μmφ or less,
Since the ratio of the minute dents to the surface is set to 10 to 40%, this surface treatment improves the oil film formation rate on the raceway surface in rolling contact, prevents early galling, and extends the life. it can.

Further, since the same surface treatment is applied to the surface of the raceway opposite to the raceway surface with which the raceway contacts rolling contact, formation of an oil film at the contact portion of the raceway ring with the plunger becomes sufficient.
From this point, the life can be extended.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the thrust rolling bearing 9 is composed of two races 10 using flat rings.
And thirteen rolling bearings 9 arranged at fixed intervals by a cage 13, and this thrust rolling bearing 9 is incorporated and used in a swash plate 3 of a hydraulic pump. The other bearing ring 11, which is housed in the housing 14 of the swash plate 3 and held in an inclined arrangement and relatively rotates with the housing 14, which is a fixed member to which the thrust rolling bearing 9 is attached, is a rolling raceway surface that comes into contact with the rolling element 12. 11
The surface on the opposite side to the surface a is the contact surface of the plunger 5, and the surface of the bearing ring 11 is a micro-rough surface a in which an infinite number of independent micro-dents are randomly formed by special barrel polishing. The fine rough surface a may be referred to as special surface processing.

FIG. 3 shows a cross-sectional roughness shape of the micro-rough surface a. As shown in FIG. 3, a special surface is formed such that a concave portion is formed on a flat surface and no convex portion is formed from the flat surface.

The average area of the fine dents on the fine rough surface a is 35 when arranged except for an equivalent circular diameter of 3 μmφ or less.
１５０150 μm ² , the proportion of the micro-dents occupying the surface is 10-40%.

The surface roughness of the micro-rough surface a is Rm on average.
ax 0.6 to 2.5 μm, and the parameter SK value of the surface roughness is −1.6 or less.

The parameter SK value refers to the degree of distortion (SKEWNESS) of the distribution curve of the surface roughness, and the SK value of a target shape distribution such as a Gaussian distribution is 0, but the parameter SK value is the value of the surface concave portion. The shape and distribution are in an advantageous range for forming an oil film, and the pits form an oil pool at the rolling contact portion, and serve to supply oil to the contact portion.

Therefore, by this surface treatment, the race 11
The oil film formation rate of the rolling raceway surface 11a contacting the rolling element 12 is improved, the occurrence of early galling of the raceway surface 11a can be prevented, and the life of the bearing ring 11 can be extended.

As shown in FIG. 2, the bearing ring 11 which comes into rolling contact with a thrust load is a component in which the rolling contact surface 11a and the contact surface of the plunger 5 are located close to each other. Processing a special surface only on the contact surface requires means such as masking, which increases the processing cost. Therefore, it is desirable that this special surface processing has a long life effect even on the contact surface.

Therefore, first, the effect of rolling contact on a micro-rough surface will be described.

The test bearing is a needle bearing 21 shown in FIG.
The surface of the roller 22 was given different conditions such as the area ratio of the fine dents and the average area of the concave portions, and a durability life test was performed with a radial load.

The roller 22 has a diameter of 5 mm and a length L of 13 m.
m is a needle roller with a retainer 23 having an inscribed inner diameter dr of 28 mm. The tester used is a radial load tester 31 as schematically shown in FIG. 5, in which test bearings are mounted on both sides of a rotating shaft 32, and a test is performed by applying rotation and load. The finish of the inner race used in the test is Rmax 2 μm of the grinding finish, and the outer race has the finish of Rmax 1.6 μm of the grinding finish. The test conditions are as follows. Bearing radial load 1465 kgf Shaft rotation speed 3050 rpm Lubricating oil Turbine oil The results of the durability life performed on each test bearing under the above conditions are shown in FIGS. 6 and 7.

FIG. 6 shows the relationship between the area ratio of the minute dents and the durable life, and FIG. 7 shows the relationship between the average area of the minute dents and the durable life.

From the above results, those having a rolling durability life of 10% or more in area ratio and 35 μm ² or more in average area
Great long life effect.

Area ratio 40% or more, average area 150 μm
The above is a reduction in the effective contact area, which has little effect in terms of the durability life.

Next, in the case of use as shown in FIG. 2, the plunger 5 is pressed against the surface of the bearing ring opposite to the raceway surface, and the abrasion resistance and the abrasion resistance of the conventional finished surface and the micro-rough surface a are reduced. The result of confirming the seizure property will be described.

The test conditions are as follows.

FA = 1200 kgf N = 2600 rpm Test time = 160 Hr As a result of the above test, the conventional finished surface had an early galling at the contact portion of the plunger in the raceway ring, whereas the contact portion of the plunger 5 had a fine rough surface a There was no early galling of the bearing ring of the present invention.

The preferred condition of the micro-rough surface a is preferably a range that satisfies both the seizure resistance of the preceding rolling surface, the rolling fatigue life, and the sliding friction resistance of the contact surface.

[0027]

As described above, according to the present invention, an infinite number of independent small depressions are randomly provided on the surface of the raceway of a thrust rolling bearing, and the average area of the small depressions is arranged except for an equivalent circular diameter of 3 μmφ or less. Sometimes 35-150 μm
^{2. The} proportion of the micro-dents on the surface is 10-40%
Therefore, the following effects can be obtained.

(I) A random micro-roughened surface provided on the rolling contact surface of the bearing ring can surely form an oil film, and the life of the thrust rolling bearing can be extended.

(II) The random micro-rough surface provided on the rolling contact surface of the bearing ring easily forms an oil film, and the fine dents form an oil pool, so that the oil film on the rolling surface can be reliably formed. Can be reduced.

(III) Since an oil film can be efficiently and reliably formed on the rolling surface, seizure resistance of the thrust rolling bearing can be improved, and early galling can be prevented.

(IV) Since an oil film can be efficiently and reliably formed on the rolling surface, it is possible to reduce torque and temperature rise.

(V) By reducing the torque and improving the seizure resistance, the durability can be improved, and the life can be extended.

(VI) A bearing ring having a random micro-rough surface on the side opposite to the rolling contact surface also improves the durability of the contact surface against which the plunger is pressed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a hydraulic pump.

FIG. 2 is an enlarged cross-sectional view of the thrust rolling bearing according to the first embodiment;

FIG. 3 is a cross-sectional view showing a surface roughness state of a track in a thrust rolling bearing.

FIG. 4 is a sectional view of a needle bearing.

FIG. 5 is a schematic drawing of a life test apparatus.

FIG. 6 is a graph showing the results of a life test apparatus.

FIG. 7 is a graph showing the results of a life test apparatus.

[Explanation of symbols]

 Reference Signs List 9 thrust rolling bearing 10, 11 raceway ring 12 roller or steel ball rolling element 13 cage 14 housing a micro rough surface

Claims (1)

(57) [Claims] 1. A rolling device in which a bearing is arranged between two raceway surfaces.
A number of independent small indentations are randomly provided on the surface of the bearing ring that rotates relative to the fixing member to which the transfer is attached. The average area of these indentations is equivalent to an equivalent circular diameter of 3.
35 to 150 μm ² when arranged except for μmφ or less,
Thrust rolling bearing is characterized in that a 10-40% proportion bur occupying the surface of the minute depressions.