JP3517266B2 - Grease-filled 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 grease-filled rolling bearing in which a rolling element is lubricated by a grease filled in a bearing, and in particular, a peeling phenomenon with a peculiar rolling surface due to a special use condition of the bearing. The present invention relates to a structure that prevents

[0002]

2. Description of the Related Art With the recent miniaturization and weight reduction of automobiles, the electrical components and accessories of the automobiles have become smaller and lighter and have higher performance.
High output is required, but in order to meet this demand,
Recent accessories and the like compensate for the decrease in output due to miniaturization by increasing the speed.

Therefore, in a drive system of an automobile engine as shown in FIG. 3, for example, an idler pulley 23 of a belt 22 for driving a gear pump 21 for power steering receives a high load and a high load during operation of the engine. In addition, the bearing that supports the idler pulley 23,
High-speed rotation, high temperature, high vibration, and high load act simultaneously.

Conventionally, a rolling element held by a retainer is mounted between inner and outer races in a bearing of an auxiliary machine such as the above idler pulley, and the rolling element is lubricated with grease enclosed in the bearing. Encapsulated rolling bearings are widely used, but recently, in this type of rolling bearing, with the high-speed rotation and high load of operating conditions, peculiar separation occurs on the rolling surface of the bearing ring, and Has been reported to reach the end of its life. This peeling phenomenon is different from peeling that occurs at a normal maximum shear stress position due to metal fatigue, and is characterized in that a crack progresses in a depth direction from a certain depth position from a rolling surface.

In order to cope with such a peeling phenomenon, the present applicant has disclosed in Japanese Patent Application No. 2-190615 that the cause of the above-mentioned peculiar peeling is that hydrogen decomposed from grease penetrates into the inside of steel. It is presumed that hydrogen embrittlement occurs, and as shown in FIG. 4, the rolling surface 3 of the inner and outer races 31, 32 is
It proposes a rolling bearing in which the surfaces of Nos. 3 and 34 are coated with an oxide film 35 and passivated.

As described above, by covering the rolling surfaces 33 and 34 with the chemically stable oxide film 35, it is possible to prevent generation of hydrogen due to the chemical decomposition of grease and the intrusion into the steel.
It has the effect of preventing the occurrence of specific peeling.

[0007]

However, in the above-proposed bearing, the oxide film 35 covering the rolling surfaces 33 and 34 is used.
Is certainly effective in preventing the occurrence of peculiar peeling, but the thicker the film 35, the more the rolling surface 3
The surface roughness of Nos. 3 and 34 deteriorates, which may cause seizure and the like at an early stage during high speed rotation.

For this reason, the thickness of the oxide film 35 must be set within a range that can prevent generation and intrusion of hydrogen and does not deteriorate the surface roughness of the rolling surface. There is a problem that it is extremely small and difficult to set. That is, in order to control the thickness of the coating within the above-mentioned appropriate range, it is necessary to strictly control the coating formation processing time, which significantly complicates the bearing production process and increases the cost. There is a problem that is forced.

The present invention has been made to solve the above-mentioned problems, and in use under high speed rotation and high load, peculiar peeling without strictly adjusting the thickness of the film formed on the rolling surface. It is an object of the present invention to provide a grease-filled rolling bearing that can prevent the occurrence of the above and realize a stable durable life.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a rolling element incorporated between rolling surfaces of inner and outer races by press punching an annular steel cage.
In a grease-filled rolling bearing in which grease is filled between both bearing rings and stored in a formed pocket for guidance,
A soft metal having a self-lubricating property is added to the pocket guide surface of the cage to prevent the permeation of hydrogen.

Further, the rolling bearing of the present invention has a soft metal film on the rolling surfaces of both races and the pocket guide surface of the cage, and the metal film of the rolling surface is formed on the pocket guide surface of the cage. It was assumed that the added metal was transformed.

The metal added to the pocket guide surface of the cage may be a copper-based metal plating layer.

[0013]

In the bearing having the above structure, when the rolling element rotates, the soft metal added to the pocket surface of the cage transfers to the surface of the rolling surface through the rolling element to form a metal film. However, this metal film prevents hydrogen from entering the steel.

In this structure, since no coating is provided on the rolling surface when the bearing is assembled and the bearing is transferred from the cage by the rotation of the bearing, the film forming treatment and the thickness of the coating are strictly set on the rolling surface. No need. In addition, early seizure due to the surface roughness of the rolling contact surface is concentrated in the initial stage of the rotation start of the bearing.By reducing the effect of the film on the rolling contact surface at the initial stage of rotation start, seizure may occur. Can be effectively prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the attached FIGS. The bearing shown in FIG. 1 shows the ball bearing 1 used to support the idler pulley 23 of the vehicle drive system shown in FIG. 3, and the state of FIG. 1 is the assembled state of the ball bearing 1 (state before operation). Is shown.

The ball bearing 1 includes an inner ring 2, an outer ring 3, a plurality of steel balls 4 interposed between the inner and outer rings 2 and 3, and a retainer 5 rotatably holding each of the steel balls 4. And the rolling surfaces 6 and 7 on which the steel balls 4 roll are formed on the surfaces of the inner ring 2 and the outer ring 3 that face each other.

Further, a pair of sealing seals 8 and 8 are attached to both sides of the respective facing surfaces of the inner ring 2 and the outer ring 3, and the steel balls 4 and the rolling surface 6 are provided inside the seals 8 and 8. Grease 9 for lubricating 7 is enclosed.

The cage 5 is an annular body made of steel plate, and a plurality of pockets 10 for accommodating the steel balls 4 are formed on the peripheral surface of the cage 5 by punching with a press. An arcuate guide surface 11 is formed inside the pocket 10, and the guide surface 11 contacts the surface of the steel ball 4 to guide the movement of the steel ball 4.

The surface of the cage 5 is pre-plated with copper before assembly into a bearing, and a soft copper thin film 12 having a thickness of 20 to 30 μm is formed on the entire surface of the cage 5. It has become.

In the ball bearing 1 assembled as described above, when the operation of the bearing is started and the steel ball 4 rotates, a part of the copper thin film 12 formed on the guide surface 11 of the pocket 10 is caused by the steel ball 4. The inner ring 2 is scraped off and the steel balls 4
To the rolling surface 6 or the rolling surface 7 of the outer ring 3. Then, the transferred copper is transferred to the rolling surfaces 6 and 7 as shown in FIG.
A soft copper thin film 12 'is formed on the surface of the.

Since the copper thin film 12 'transferred to the rolling surface does not allow the permeation of hydrogen molecules, it prevents the hydrogen chemically decomposed from the grease 9 from entering the steel of the inner and outer races 2 and 3 and is unique. Prevents the occurrence of exfoliation.

Further, since the copper thin film 12 'itself has an excellent self-lubricating action, it reduces the frictional resistance between the rolling surfaces 6 and 7 and the steel balls 4, and seizure which tends to occur at the beginning of the operation. It has the effect of preventing the phenomenon.

Such a copper thin film 12 and 12 'has a thickness higher than that of steel.
Since it is a few steps soft, the transition speed is fast and
It is transferred to rolling surfaces 6 and 7 in an extremely short time due to rolling.
Form a smooth thin film. Gold with this kind of properties
As the metal thin film, in addition to copper and its alloys, lead, silver,Money,
Examples thereof include tin and its alloys.

Although the copper thin film 12 is provided on the entire surface of the retainer 5 in the above embodiment, it may be provided at least only on the guide surface 11 of the pocket 10 that contacts the steel ball 4. It is possible to obtain the transition effect of the steel balls.

Further, the type of the cage 5 is not limited to the one made of the above-mentioned steel plate, but may be a machined cage in which pockets are formed by machine cutting. In this case, a copper thin film can be formed on the surface of the pocket using a method such as thermal spraying.

[0026]

[Effects] The present invention having the above-mentioned structure has the following special effects as a grease-filled rolling bearing.

(1) Under the special condition that the surface of the rolling surface locally becomes high temperature and high pressure due to the motion of the rolling element rotating at high speed, the metal film transferred to the rolling surface acts as a covering, Since hydrogen generated from the grease is prevented from entering the steel from the rolling contact surface of the bearing, the occurrence of specific exfoliation can be prevented.

(2) Prevent the seizure in the initial stage of the bearing because the soft metal peeled off from the cage at the initial stage of bearing rotation instantly transfers to the rolling surface through the steel balls and forms a smooth thin film. You can

(3) Since the peculiar exfoliation of the bearing under special conditions can be effectively prevented with a simple structure,
There is no significant increase in bearing cost, and the effect on the production process is great.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an assembled state of a ball bearing of an embodiment.

FIG. 2 is a partial cross-sectional view showing a state of the above ball bearing after the start of operation.

FIG. 3 is an explanatory diagram showing a drive system of an automobile accessory in which the above ball bearing is used.

FIG. 4 is a partial sectional view showing a conventional example.

[Explanation of symbols]

1 ball bearing 2 inner ring 3 outer ring 4 steel balls 5 cage 6,7 Rolling surface 8 seals 9 grease 10 pockets 11 guideway 12,12 'Copper thin film

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-2-190615 (JP, A) JP-A-63-43024 (JP, A) JP-A-4-282023 (JP, A) JP-A-3- 210394 (JP, A) JP 4-160225 (JP, A) JP 5-196047 (JP, A) JP 7-91450 (JP, A) Actual development Sho 63-78723 (JP, U) Actual development Sho 56-62661 (JP, U) Japanese patent publication Sho 37-4054 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16C 19/00-19/56 F16C 33/00 -33/66

Claims (3)

(57) [Claims] 1. A rolling element incorporated between transfer surfaces of inner and outer races is formed by press punching an annular steel cage.
In a grease-filled rolling bearing that is housed in a pocket that is formed and guided, and grease is filled between the two bearing rings, the pocket guide surface of the cage prevents the penetration of hydrogen and is a soft, self-lubricating material. A grease-filled rolling bearing characterized by the addition of metal. 2. A soft metal coating is provided on the rolling surfaces of the bearing rings and the pocket guide surface of the cage, and the metal coating on the rolling surface transfers the metal added to the pocket guide surface of the cage. The rolling bearing according to claim 1, wherein the rolling bearing is filled with grease. 3. The grease-filled rolling bearing according to claim 1, wherein the metal added to the pocket guide surface of the cage is a copper-based metal plating layer.