JP2003343590A - Creep preventive bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a creep preventive bearing which surely prevents a creep even under a high-temperature using condition exceeding 100°C. <P>SOLUTION: The creep preventive bearing comprises a groove 4 extended in a circumferential direction formed on the outer peripheral surface of the bearing, and a strip-like spacer 5 made of a resin engaged with the groove 4 and provided in the axial dial direction set to the thickness direction. In this bearing, the thickness (d) in the axial radial direction of the spacer 5 satisfies a formula (1) of a low water absorbable resin having a water absorbable rate (ASTM D570) of 1% of less, (wherein (d) is a thickness [mm] of the spacer in the axial dial direction, SD is the outer diameter of the bearing, ΔT is a different [°C] between the assumed using temperature higher than the ambient temperature and a reference temperature (ambient temperature), αis the linear expansion coefficient of the resin layer [1/°C], β is the linear expansion coefficient [1/°C] of the bearing material, and γ is the linear expansion coefficient [1/°C] of a shaft case material). <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 creep-preventing bearing in which a belt-shaped spacer made of resin is attached to the outer diameter surface of the bearing, and a method of designing the same.

[0002]

2. Description of the Related Art In order to reduce the weight of a device, it is necessary to reduce the weight of a shaft box (housing) for holding a bearing. For example, a structure in which a steel rolling bearing is held in a shaft box made of an aluminum alloy is adopted. ing.

When the shaft case is made of a metal different from that of the bearing outer ring, when used in a high temperature environment, a gap is formed between the bearing material and the shaft box material due to the difference in the coefficient of thermal expansion between them.
The bearing may lose the fixed supporting force from the housing and cause a relative "deviation" in the rotation direction of the shaft, causing a phenomenon called "creep".

When such "creep" progresses, abnormal wear (so-called fretting) occurs due to reciprocating friction of small amplitude on the shaft box and the outer diameter surface. If this frequently occurs, the fixed support of the bearing is insufficient. become.

In order to prevent creep, the conventional creep prevention bearing has a resin band-shaped spacer attached to the outer diameter surface of the outer ring of the bearing.

Japanese Unexamined Patent Publication No. 7-60556 discloses nylon 6, nylon 11, nylon 4 on the outer surface of the outer ring of the bearing.
6, a creep-preventing rolling bearing provided with a strip spacer made of nylon 66 is described.

In Japanese Patent Laid-Open No. 6-159375, when a polyether sulfone is used as the material of the strip spacer as a creep-preventing rolling bearing in which a strip spacer is attached to the outer surface of the outer ring of the bearing, the water absorption is small. However, since this resin is amorphous, there is little influence of shrinkage due to crystallization.

[0008]

However, in the conventional anti-creep rolling bearings described above, there are many combinations of materials and sizes of the shaft box, the bearing outer ring, and the spacer.
In order to surely prevent the creep under each condition, a complicated experimental method or the like is required to provide the resin-made spacers.

For example, even if the bearing can surely prevent creep at a predetermined expected operating temperature, how much the thickness of the spacer should be increased in order to prevent creep under unexpected temperature conditions. When the material of the outer ring or axle box is changed according to weight reduction, heat resistance and other conditions,
It is necessary to set the reliability of the spacer such that the thickness should be changed, but it was difficult to design without repeated trials.

In some greases used at high temperatures, ester oil may be mixed as a base oil. However, ester oil may deteriorate the strength of synthetic resin. A problem that a polyether sulfone (PES) resin composition having heat resistance and dimensional stability preferable as a resin for a belt-shaped spacer made of a resin provided between shaft boxes is deteriorated and cracks are easily generated. There is.

Therefore, an object of the present invention is to solve the above-mentioned problems, and the resin band-shaped spacer provided between the outer ring of the creep preventing bearing and the shaft box is used under high temperature conditions such that it exceeds 100.degree. Also in the above, the bearing is to be surely expanded to a predetermined size to have an appropriate thickness, and creep can be surely prevented.

Further, the chemical resistance of the resin band-shaped spacer provided between the outer ring of the creep prevention bearing and the shaft box is increased,
In particular, it is to provide a creep-preventing bearing which is excellent in ester oil resistance and also excellent in preventing cracks in the strip spacer.

[0013]

In order to solve the above-mentioned problems, in the present invention, a groove extending in the circumferential direction is formed on the outer diameter surface of the bearing, and a resin-made belt-like spacer fitted in the groove is used as the shaft. A creep prevention bearing provided with a predetermined thickness in the radial direction, characterized in that the thickness d in the axial direction of the belt-like spacer is set to a thickness that satisfies the following formula (2). I did.

[0014]

[Equation 2]

(Where d is the thickness [mm] of the spacer in the axial direction, D is the bearing outer diameter, ΔT is the difference [° C] between the assumed operating temperature higher than room temperature and the reference temperature (room temperature), and α is The linear expansion coefficient of the resin layer [1 / ° C], β is the linear expansion coefficient of the bearing material [1 /
[° C.], γ indicates the linear expansion coefficient [1 / ° C.] of the shaft box material. According to the creep prevention bearing of the present invention configured as described above, the spacer thickness is changed according to the above equation 2 to determine the outer diameter of the bearing, the coefficient of thermal expansion different for each resin type, the heat of the bearing material and the shaft box material. By providing a predetermined thickness that corresponds to the expansion coefficient, the volume of resin that expands is larger than the volume of the groove that increases when the temperature rises by ΔT, and the diameter dimension is reliably increased to prevent creep. It will be possible.

Further, it is preferable to employ a low water-absorbing resin having a water absorption rate (ASTM D570) of 1% or less as the resin for forming the belt-like spacers. In this case, it is possible to surely prevent the creep even under high temperature use conditions. Can be an excellent anti-creep rolling bearing.

If the resin forming the strip spacer is a crystalline resin, the creep-preventing rolling bearing having the above-mentioned structure will be a creep-preventing rolling bearing having a strip spacer excellent in chemical resistance and oil resistance. Even if ester oil is contained in the grease leaked from the bearing, or if a substance that is chemically aggressive to the resin (high in chemical attack) is used as a rust preventive agent, the strip spacer will be attacked. It is a creep-preventing rolling bearing that is hard to crack and hard to crack.

Furthermore, it is preferable that the creep-preventing rolling bearing having the above-mentioned constitution is one in which the resin forming the strip-shaped spacer is a resin having a glass transition temperature of 100 ° C. or higher and a glass transition temperature as high as possible. Under the use condition where the glass transition temperature is not exceeded, the resin is not plastically deformed, but can be frictionally engaged with the axle box by the elastic force, so that the creep is surely prevented. If the resin forming the strip-shaped spacer has a glass transition temperature of less than 100 ° C., the creep preventing property cannot be reliably exhibited under high temperature use conditions of 100 ° C. or higher.

In order to solve the above-mentioned problems and to design a creep prevention bearing capable of reliably preventing creep, a groove extending in the circumferential direction is formed on the outer diameter surface of the bearing, and a resin band spacer fitted in the groove. In the method for designing a creep preventing bearing in which is provided with a predetermined thickness in the axial radial direction, the belt-shaped spacer is designed so that the axial radial thickness d satisfies the equation (2). It is also possible to adopt the design method of the creep prevention bearing.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the creep prevention bearing of the embodiment comprises an inner ring 1, an outer ring 2, and a rolling element 3 made of bearing steel, and a cage (not shown) made of mild steel or resin. A groove that surrounds the outer diameter surface of the outer ring 2 (circumferential groove)
4 is formed, and a resin ring-shaped strip spacer 5 is provided in the groove 4 by injection molding so as to have a predetermined thickness d in the axial direction.

To mount the produced creep-preventing bearing on the axle box 6, the bearing is inserted into the axle box 6 made of metal such as aluminum alloy, and at that time, the strip spacer 5 is provided between the axle box 6 and the outer ring 2. The outer peripheral surface of the belt-shaped spacer 5 is pressed against the wall surface of the shaft box 6 so that the radial elastic force acts on the shaft box 6 and fixed by the frictional engagement force.

The groove 4 may be machined into one or more rows on the outer diameter surface of the outer ring 2 of the bearing, or may be formed at the same time as the outer ring is formed. Is formed. Then, the outer diameter surface of the strip-shaped spacer 5 is slightly projected from the outer diameter surface of the outer ring 2 or is adjusted so as to form the same plane. Further, the groove 4 may be formed as a so-called peripheral groove that is continuous in the circumferential direction, or may be formed as a discontinuous peripheral groove.

Then, when the strip-shaped spacer 5 is injection-molded into the groove 4 or a separately formed one is fitted, 90% or more of the radial thickness of the strip-shaped spacer 5 is accommodated in the groove 4. Is preferred. This is because when the depth of accommodating the strip spacer 5 in the groove 4 is less than 90% of the radial thickness,
This is because it is expected that when heated, the volume increase of the strip spacer 5 expands in the axial direction of the bearing and the fitting clearance in the diametrical direction may not be sufficiently adjusted.

As shown in FIG. 1, the strip-shaped spacers 5 may be provided in one row with an arbitrary width having a shape and size that can fit into the groove 4, and as shown in FIG. It can also be provided on the strip spacers 7 in a row.

As a preferable groove shape, the surface area of the inner wall surface is increased, or the bottom surface and the side surface are roughened by a chemical or physical surface treatment, or the adhesive force is increased to shift the position in the circumferential direction. It is a shape that can prevent.

For example, the groove 4 shown in FIG. 3 has a linear bulging portion 4a formed along one corner of the bottom surface, and the belt-shaped spacer 5 (FIG. 1) is engaged in this portion to engage with the groove 4. The area is made large, thereby preventing "slip movement (creep)" of the strip spacer 5 around the axis.

As the material of the strip-shaped spacer provided in such a form, it is preferable to adopt a low water-absorbing resin having a water absorption rate (ASTM D570) of 1% or less.

Further, the resin band-shaped spacer is
T570 (A test piece with a thickness of 3 mm was placed in water at 23 ° C for 24
It is preferable to use a resin that shows a measured value of 1% or less when immersed for a long time so that there is no dimensional change with respect to the humidity of the working atmosphere and the "fitting" to the axle box is stable, while the water absorption is When the resin is larger than 1%, when it is heated, the water contained therein evaporates and shrinks, so that the original creep property cannot be sufficiently exhibited.

Specific examples of the low water absorption resin having a water absorption rate (ASTM D570) of 1% or less include 11 nylon and 12
Nylon, polyacetal resin, PBT resin, 6T nylon, 9T nylon, ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA)
Is mentioned. Of these, the band-shaped spacer may be formed using a resin composition in which two or more kinds of resins are mixed.
In particular, by using 9T nylon (also called nylon 9T), the bearing can be continuously used in a high temperature atmosphere of 150 ° C.

Incidentally, 9T nylon is a crystalline resin in which the polymer repeating unit is composed of nonanediamine, which is a diamine having 9 carbon atoms, and terephthalic acid, and has a high crystallization rate and a high glass transition temperature of 126 ° C. It is a resin that does not easily deform even at a high temperature of 100 ° C or higher (below the glass transition point). An example of a commercially available 9T nylon product is Genestar manufactured by Kuraray Co., Ltd.

As the low water-absorbent resin, well-known additives may be added. For example, glass fiber, carbon fiber, fibrous filler such as potassium titanate whisker, and particulate filler such as graphite and calcium carbonate. It may be blended, and it is also preferable to blend polyethylene or an elastomer in order to further increase the linear expansion coefficient.

As a method of molding the resin-made belt-shaped spacer, separately, a long-shaped one is cut appropriately according to the length of the groove, or the outer ring is fitted into a mold, and the molten resin is grooved. Productivity is good if the method of injection molding is adopted. The predetermined thickness in the radial direction of the strip-shaped spacer can be adjusted by adjusting the size of the molding die and mechanically cutting after molding. Furthermore, it is also preferable to carry out an annealing treatment for dimensional stabilization.

The mechanism of the creep preventing bearing in the present invention is not particularly limited to what is called a type, and when the rolling bearing is a rolling bearing, the type of rolling element is a ball, a roller (including a needle roller), or a conical roller. The bearing mechanism may be a bearing mechanism of a known type, or may be a plain bearing having no rolling element.

By using the creep preventing bearing as described above, a bearing having excellent heat resistance that can withstand a temperature rise due to improvement in engine efficiency even when used in the vicinity of the engine room, as a bearing used in automobile electrical components. can do.

[0036]

EXAMPLES AND COMPARATIVE EXAMPLES Resin materials for the strip spacers used in Examples and Comparative Examples are listed below. In addition, []
Is an abbreviation shown in the table below, and Tg represents a glass transition temperature. 9T Nylon [PA9T] (Kuraray Co., Ltd .: Genesta, Tg = 126 ° C.) 11 Nylon [PA11] (Atofina Japan Co., Ltd .: Rilsan BMN) Polyacetal resin [POM] (Polyplastics Co., Ltd .: Duracon M90-02) 46 Nylon [PA46] (DSM JSR Engineering Plastics: Stany KS300, Tg = 78 ° C) 66 Nylon [PA66] (Toray: CM3001N,
Tg = 66 ° C.) [Examples 1 to 3, Comparative Examples 1 to 4] 40 mm outer diameter, 1 inner diameter
Two 2 mm wide circumferential grooves were formed at 2 mm intervals on the outer diameter surface of a deep groove ball bearing having a width of 7 mm and a width of 12 mm (the coefficient of linear expansion of the bearing steel being 1.18 × 10 ⁻⁵ / ° C.).

Next, a mold is fitted so as to cover the outer circumference of the bearing, and the resin shown in Table 1 is melted and injected into the mold to form a ring-shaped band-shaped spacer (with an outer diameter of 4 mm and an outer diameter of 4 mm).
0.04 mm) is the thickness (mm) in the axial direction shown in the table.
Composite injection molding was performed so that

Next, the injection-molded strip spacer was cut and polished so that it protruded by 20 μm from the outer diameter surface of the bearing. In addition, all the dimensions show the values measured at 23 ° C. (reference temperature).

The test bearings thus obtained were subjected to the following tests a and b. In this test, the water absorption rate (ASTM T570 measurement value (%)) of each strip spacer was examined, and the coefficient of linear expansion and the thickness (mm) in the axial direction at 100 ° C and 180 ° C calculated from this were shown in Table 1. Also described in.

[0040]

[Table 1]

(A) Creep test Cylindrical shaft box 8 (inner diameter 40.40 to 40.5 shown in FIG. 4)
0 mm) was prepared and the test bearing A inserted from the large diameter portion was erected on the flat base 9 as shown in the drawing, and 1
A load of 9.6 N (load G) was applied. 10 in this state
The bearings were placed in an electric furnace set at 0 ° C or 180 ° C for 24 hours and then returned to room temperature, and the bearing positions were examined. The results did not deviate from the initial position (○ mark) or deviated (Δ mark). ), And the evaluation was made in three stages of falling to the bottom (marked with X), and this is shown in Table 2 by a symbol in parentheses.

(B) Dimensional Change Test by Drying The test bearing was dried at 80 ° C. for 8 hours, and the outer diameter of the strip spacer (ring) before and after this drying treatment was measured,
The results are shown in Table 2.

[0043]

[Table 2]

As is clear from the results shown in Tables 1 and 2, Comparative Examples 3 and 4 using the resin having a water absorption rate of more than 1% had a very large dimensional change rate. The outer diameter of the spacer was smaller than the outer diameter of the bearing outer ring, and the amount of dimensional change could not be measured accurately. Further, in Comparative Examples 1 and 2 in which the thickness of the strip-shaped spacer was formed to be smaller than the calculated value d, creep occurred in the bearing under any temperature condition.

On the other hand, in Examples 1 to 3 in which the resin having a water absorption rate of less than 1% was used, the dimensional change amount was small,
It withstands practical use, and there was no displacement of the bearing in the shaft box in the 100 ° C storage test. Also, 9T
The bearing of Example 1 using nylon has a high temperature of 100 ° C.
Creep could be prevented not only in the test but also in the 180 ° C. test.

[0046]

As described above, the present invention is used as a creep-preventing bearing having a belt-shaped spacer fitted in a groove extending in the circumferential direction on the outer diameter surface of the bearing and having a predetermined thickness in the axial radial direction. Thus, there is an advantage that the diameter can be surely increased due to expansion when the temperature rises, and the creep prevention bearing can surely prevent creep even under high temperature use conditions such as exceeding 100 ° C.

Further, by adopting a low water absorbing resin having a water absorption rate of 1% or less as the resin forming the belt-like spacer, shrinkage due to drying is small, and creep can be reliably prevented under high temperature use conditions. become.

If the resin forming the strip spacer is a crystalline resin, the creep-preventing rolling bearing having the above-mentioned construction is provided with the strip-preventing rolling bearing excellent in chemical resistance and oil resistance against ester oil and the like. Become a bearing.

Furthermore, if the resin forming the belt-shaped spacer has a glass transition temperature of 100 ° C. or higher, it will be a rolling bearing that reliably prevents creep under operating conditions in which the glass transition temperature is not exceeded.

[Brief description of drawings]

FIG. 1 is a radial cross-sectional view showing a main part of a creep prevention bearing according to a first embodiment.

FIG. 2 is a radial cross-sectional view showing the main parts of the creep prevention bearing of the second embodiment.

FIG. 3 is an enlarged radial cross-sectional view showing the main part of the outer ring of the creep prevention bearing of the second embodiment.

FIG. 4 is a radial cross-sectional view of a shaft box and a bearing for explaining the creep test method.

[Explanation of symbols]

1 inner ring 2 outer ring 3 rolling elements 4 grooves 5,7 Strip spacer 6, 8 axis box 9 bases A test bearing G load

Claims (4)

[Claims] 1. A creep-preventing bearing, wherein a groove extending in a circumferential direction is formed on an outer diameter surface of a bearing, and a resin band spacer fitted in the groove is provided in a predetermined thickness in an axial radial direction. A creep prevention bearing characterized in that the thickness d in the axial direction of is set to a thickness that satisfies the following formula (1). [Equation 1] (In the formula, d is the thickness [mm] of the strip spacer in the axial direction,
D is the outer diameter of the bearing, ΔT is the difference [° C] between the assumed operating temperature higher than room temperature and the reference temperature (room temperature), α is the linear expansion coefficient of the resin layer [1 / ° C], and β is the linear expansion coefficient of the bearing material [ 1 / ° C.] and γ represent the linear expansion coefficient [1 / ° C.] of the shaft box material. ) 2. The anti-creep rolling bearing according to claim 1, wherein the resin forming the strip-shaped spacer is a low water absorption resin having a water absorption rate (ASTM D570) of 1% or less. 3. The creep preventing rolling bearing according to claim 1, wherein the resin forming the strip spacer is a crystalline resin. 4. The anti-creep rolling bearing according to claim 1, wherein the resin forming the strip-shaped spacer is a resin having a glass transition temperature of 100 ° C. or higher.