JP2010090984A - Creep prevention rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To design a resin-made band to a size capable of being used in a range of temperature irrespective of service temperature of a bearing. <P>SOLUTION: The resin-made band 7 is installed to fill up an annular groove 6 of an outer ring 2. The ratio d/D of the inner diameter d and the outer diameter D of the band 7 satisfies formula, d/D≤√[(2α<SB>H</SB>-3α<SB>B</SB>+α<SB>R</SB>)/ä3(α<SB>R</SB>-α<SB>B</SB>)}], wherein the coefficient of linear expansion of an aluminum alloy forming a housing 10 is represented by α<SB>H</SB>(/K), the coefficient of linear expansion of a high-carbon chromium bearing-steel forming the outer ring 2 is represented by α<SB>R</SB>(/K), the coefficient of linear expansion of the resin forming the band 7 is represented by α<SB>B</SB>(/K). By specifying the size of the band 7 as described above, the band 7 is designed to a size capable of being used in a wide range of temperature irrespective of service temperature of a bearing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an anti-creep rolling bearing that prevents creep of an outer ring fitted in a housing.

  2. Description of the Related Art Some auxiliary housings for automobiles such as alternators are made of a light metal having a low specific gravity such as aluminum, magnesium, or one or both of these alloys for weight reduction. All of these light metals have a larger linear expansion coefficient than steel.

  In a rolling bearing in which an outer ring formed of steel is fitted in a housing formed of a metal having a larger linear expansion coefficient than that of steel, the outer ring is caused by a decrease in tightening allowance due to a difference in thermal expansion between the housing and the outer ring. In order to prevent creep, an annular groove extending in the circumferential direction is provided on the outer diameter surface of the outer ring, and a band formed of a resin having a linear expansion coefficient larger than that of the housing protrudes from the outer diameter surface of the outer ring. An anti-creep rolling bearing that is mounted as described above is used (see, for example, Patent Document 1).

  In the one described in Patent Document 1, the housing, the outer ring, and the band in which the radial thickness of the resin band with respect to the outer diameter of the bearing is a parameter of the temperature difference between the assumed operating temperature of the bearing higher than room temperature and the room temperature. It is specified by a function of each linear expansion coefficient.

  As the resin forming the band, polyamide 9T (PA9T), polyamide 11 (PA11), polyamide 66 (PA66), polybutylene terephthalate (PBT) or the like is used.

JP 2003-343590 A

  The anti-creep rolling bearing described in Patent Document 1 defines the radial thickness of the resin band with respect to the outer diameter of the bearing using the temperature difference between the assumed operating temperature and room temperature as a parameter. Accordingly, it is necessary to design the size of the resin band, and there is a problem of lack of versatility.

  Therefore, an object of the present invention is to design the size of the resin band so that it can be used in a wide temperature range regardless of the operating temperature of the bearing.

In order to solve the above problems, the present invention is an annular groove that is fitted in a housing formed of a metal having a larger linear expansion coefficient than steel and extends in the circumferential direction on the outer diameter surface of the outer ring formed of steel. In the anti-creep rolling bearing in which a band formed of a resin having a larger linear expansion coefficient than the metal forming the housing is mounted in the annular groove so as to protrude from the outer diameter surface of the outer ring, the band is The metal is formed so as to fill the annular groove, the coefficient of linear expansion of the metal forming the housing is α _H (/ K), the coefficient of linear expansion of the steel forming the outer ring is α _R (/ K), When the linear expansion coefficient of the resin forming the band is α _B (/ K), the ratio d / D between the inner diameter d and the outer diameter D of the band is defined to satisfy the expression (1). Adopted the configuration.
d / D ≦ √ [(2α _H −3α _B + α _R ) / {3 (α _R −α _B )}] (1)

That is, the body expansion amount ΔV per unit temperature increase of the band mounted so as to fill the annular groove is defined as β (/ K) as the outer diameter expansion coefficient of the band, Then, it is expressed by equation (2) depending on the constraint condition by the annular groove.
ΔV = π [{D (1 + β)} ² − {d (1 + α _R )} ² ] · (1 + α _R ) · W
−π (D ² −d ² ) · W (2)
On the other hand, since the volume expansion rate of the band is three times the linear expansion coefficient alpha _B, volume expansion amount ΔV per unit temperature rise of the band can also be expressed by equation (3).
ΔV = 3α _B π (D ² −d ² ) · W (3)
If the expressions (2) and (3) are arranged and arranged, and the second and higher terms of the linear expansion coefficient α _R and the outer diameter expansion coefficient β are omitted, the outer diameter expansion coefficient β of the band is (4) Represented by the formula
β = {3α _B −α _R +3 (d / D) ² · (α _R −α _B )} / 2 (4)

In order not to lower the band tightening margin with respect to the housing, it is necessary that the outer diameter expansion coefficient β of the band is equal to or larger than the inner diameter expansion coefficient of the housing, that is, the linear expansion coefficient α _H. (5) The formula is obtained.
β = {3α _B −α _R +3 (d / D) ² · (α _R −α _B )} / 2 ≧ α _H (5)
Considering that α _R −α _B <0, the above equation (1) is obtained by arranging the equation (5) with respect to the inner / outer diameter ratio d / D of the band. Since the equation (1) does not include a temperature parameter and is a function of only the linear expansion coefficients α _H , α _R , and α _B , the size of the resin band is set so that the bearing can be used in a wide temperature range. Can be designed.

  By providing a fillet portion at at least one groove bottom corner portion of the annular groove, the resin band can be easily mounted so as to fill the annular groove.

  By providing a chamfered portion at the inner diameter side corner portion of the band that is fitted into the groove bottom corner portion provided with the fillet portion of the annular groove, the resin band can be easily fitted into the annular groove.

  By providing the annular groove at two locations on both sides of the bearing center and providing the fillet portion at the groove bottom corner portion on the bearing center side, the outer ring can be supported in a well-balanced manner by the resin band fitting tip When the chamfered portion is provided on the side, the resin band can be easily fitted by the annular groove.

  The rolling bearing is a ball bearing in which an arc-shaped raceway groove is formed on the inner diameter surface of the outer ring, and the two annular grooves are provided on both sides of the center of the arc-shaped raceway groove so that the outer ring is balanced in the housing. Can be supported.

  By setting the minimum thickness between the groove bottom corner portion on the bearing center side of the outer ring and the raceway groove to be 1 mm or more, the strength of the outer ring can be ensured.

  Each of the anti-creep rolling bearings described above is suitable for a case where the metal forming the housing is aluminum, magnesium, or one or both of these alloys.

The anti-creep rolling bearing of the present invention is mounted so that the band formed of resin fills the annular groove, the linear expansion coefficient of the metal forming the housing is α _H (/ K), and the outer ring is formed. When the linear expansion coefficient of the steel is α _R (/ K) and the linear expansion coefficient of the resin forming the band is α _B (/ K), the ratio d / D between the inner diameter d and the outer diameter D of the band is Since it has been defined so as to satisfy the expression (1), the size of the resin band can be designed so that it can be used in a wide temperature range regardless of the operating temperature of the bearing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this creep-proof rolling bearing, as shown in FIG. 1 (a), an inner ring 1 and an outer ring 2 are formed of high carbon chromium bearing steel SUJ2 (linear expansion coefficient α _R = 1.25 × 10 ⁻⁵ / K). A deep groove ball bearing in which a plurality of balls 3 are held by a cage 4 between these arc-shaped raceway grooves 1a and 2a and both ends are sealed by a seal member 5, and an aluminum alloy (linear expansion coefficient α _H = 2.18 × 10 ⁻⁵ / K) on the outer diameter surface of the outer ring 2 fitted inside the inner diameter surface of the housing 10 at two locations on both sides of the raceway groove 2a provided in the center of the bearing. An annular groove 6 extending in the direction is provided, and a band 7 made of a resin having a linear expansion coefficient α _B larger than the linear expansion coefficient α _H of the aluminum alloy forming the housing 10 is attached to each annular groove 6.

  The band 7 is mounted so as to protrude from the outer diameter surface of the outer ring 2 and fill the annular groove 6 as shown in an enlarged view in FIG. An R-shaped fillet 6a is provided at the groove bottom corner on the bearing center side of the annular groove 6, and the minimum thickness between the groove bottom corner provided with the fillet 6a and the raceway groove 2a is 1 mm or more. It is said that. The fillet portions 6a may be provided at the groove bottom corner portions on both sides, and the cross-sectional shape is not limited to the R shape. In addition, an R-shaped chamfered portion 7a that is equal to or slightly smaller than the fillet portion 6a is provided at the inner diameter side corner portion of the band 7 fitted into the groove bottom corner portion provided with the fillet portion 6a.

The ratio d / D between the inner diameter d and the outer diameter D of the band 7 is such that when the temperature rises during use, the linear expansion coefficients α _H , α _R , It is defined so as to satisfy the expression (1) that is a function of only α _B.
d / D ≦ √ [(2α _H −3α _B + α _R ) / {3 (α _R −α _B )}] (1)

As shown in Table 1, deep groove ball bearings were prepared in which the resin on which the band 7 was formed was PA9T, PA11, and PA66, respectively, and the inner / outer diameter ratio d / D was defined to satisfy the formula (1) (implementation) Examples 1-3). Further, as a comparative example, a deep groove ball bearing in which the resin on which the band 7 was formed was PA9T and the inner / outer diameter ratio d / D did not satisfy the formula (1) was also prepared. In Table 1, the outer diameter expansion coefficient β of the band 7 calculated by the equation (5) and the value on the right side of the equation (1) are also added as reference values. The expansion coefficient β is larger than the linear expansion coefficient α _{H of the} housing.

  The deep groove ball bearings of the above examples and comparative examples were subjected to a bearing rotation test for rotating the inner ring after press-fitting with a tightening margin between the band and the housing to the housing formed of the aluminum alloy of the rotation tester, The decrease in the tightening allowance due to the temperature rise during operation was investigated based on the occurrence of creep. The results of this bearing rotation test are also shown in Table 1. In the examples in which the inner / outer diameter ratio d / D is defined so as to satisfy the formula (1), creep does not occur in a wide temperature range. It was confirmed that there was no decrease in the tightening allowance associated with the temperature rise. On the other hand, it was found that the comparative example in which the inner / outer diameter ratio d / D does not satisfy the formula (1) generates creep, and the tightening margin decreases with increasing temperature.

  In the above-described embodiment, the deep groove ball bearing is provided with two resin bands in two annular grooves on the outer diameter surface of the outer ring. However, the anti-creep rolling bearing according to the present invention is an angular ball bearing or a roller bearing. The present invention can be applied to other types of rolling bearings, and the number of resin bands can be one or three or more.

  In the above-described embodiment, the outer ring is fitted in a housing formed of an aluminum alloy. However, the metal forming the housing may be any material that has a linear expansion coefficient larger than that of steel, aluminum, Magnesium, a magnesium alloy, an aluminum magnesium alloy, or the like can also be used.

a is a partially omitted longitudinal sectional view showing an embodiment of a creep preventing rolling bearing, and b is an enlarged sectional view showing a mounting portion of a resin band of a.

Explanation of symbols

Reference Signs List 1 inner ring 2 outer ring 1a, 2a raceway groove 3 ball 4 cage 5 seal member 6 annular groove 6a fillet part 7 band 7a chamfered part 10 housing

Claims (7)

A metal that is fitted in a housing made of a metal having a linear expansion coefficient larger than that of steel, and that has an annular groove extending in the circumferential direction on the outer diameter surface of the outer ring made of steel. The metal that forms the housing in the annular groove In a creep prevention rolling bearing in which a band formed of a resin having a larger linear expansion coefficient than the outer ring is mounted so as to protrude from the outer diameter surface of the outer ring, the band is mounted so as to fill the annular groove. , The linear expansion coefficient of the metal forming the housing is α _H (/ K), the linear expansion coefficient of the steel forming the outer ring is α _R (/ K), and the linear expansion coefficient of the resin forming the band is α _B A creep-proof rolling bearing characterized in that, when (/ K), the ratio d / D between the inner diameter d and the outer diameter D of the band satisfies the following formula.
d / D ≦ √ [(2α _H −3α _B + α _R ) / {3 (α _R −α _B )}]   The creep-preventing rolling bearing according to claim 1, wherein a fillet portion is provided in at least one groove bottom corner portion of the annular groove.   The creep-preventing rolling bearing according to claim 2, wherein a chamfered portion is provided at an inner diameter side corner portion of the band fitted into a groove bottom corner portion provided with a fillet portion of the annular groove.   The creep preventing rolling bearing according to claim 2 or 3, wherein the annular groove is provided at two locations on both sides of the bearing center, and the fillet portion is provided at a groove bottom corner portion on the bearing center side.   5. The creep prevention according to claim 4, wherein the rolling bearing is a ball bearing in which an arc-shaped raceway groove is formed on an inner diameter surface of the outer ring, and the two annular grooves are provided on both sides of the center of the arcuate raceway groove. Rolling bearing.   The creep-preventing rolling bearing according to claim 5, wherein a minimum thickness between a groove bottom corner portion of the outer ring on the bearing center side and the raceway groove is 1 mm or more.   The creep-preventing rolling bearing according to any one of claims 1 to 6, wherein the metal forming the housing is aluminum, magnesium, or one or both alloys thereof.

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