JP2006207684A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing free of damage such as seizure under the conditions of a high temperature and a high speed where a dm×n value (a product of a pitch circle diameter dm of a rolling element and a bearing ring rotating number n) is 60×10<SP>4</SP>or more. <P>SOLUTION: The deep groove ball bearing 10 comprises an outer ring 11 having an outer ring raceway 11a on an inner peripheral face 11b, an inner ring 12 having an inner ring raceway 12a on an outer peripheral face 12b, a plurality of balls 13 rollingly provided between the outer ring raceway 11a and the inner ring raceway 12a in the circumferential direction, and a snap cage 20 provided between the inner peripheral face 11b of the outer ring 11 and the outer peripheral face 12b of the inner ring 12 and formed of a polyamide 9T resin for rollingly holding the balls 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rolling bearing used in automobiles, motors, machine tools, and the like, and more particularly to a rolling bearing used at high speed rotation.

  Conventional ball bearings are generally press-molded as a cage that holds a plurality of rolling elements arranged in a circumferential direction between a raceway surface of an outer ring and a raceway surface of an inner ring. Iron ones are used. However, when the rotational speed of the bearing is increased, the iron cage has a problem that friction due to sliding contact between the rolling element and the cage increases, and the temperature rise of the bearing increases and seizure occurs.

  Therefore, it is considered effective to use a cage made by injection molding a synthetic resin that is superior to iron in terms of self-lubricating properties, low friction properties, light weight, etc. A polyamide 66 resin or a polyamide 46 resin is used, and a glass fiber is added and reinforced as necessary. A cage using polyamide 9T resin has also been proposed for the purpose of improving dimensional stability, heat resistance, and chemical resistance (see, for example, Patent Document 1).

JP 2001-317554 A

However, the synthetic resin has a property that mechanical properties greatly change at the boundary of the glass transition temperature, and becomes close to a rubber shape at a high temperature. The glass transition temperatures of polyamide 66 resin and polyamide 46 resin, which are general cage materials, are about 70 ° C. and about 80 ° C., respectively. Heat generation due to sliding friction increases. Furthermore, the temperature of the bearing further rises, and the cage and the outer ring may come into contact with each other, resulting in seizure. Therefore, when used at a high speed rotation where the dm · n value (the product of the rolling element pitch circle diameter dm and the raceway rotation speed n) is 60 × 10 ⁴ or more, damage due to seizure cannot be prevented. was there.
Patent Document 1 proposes a cage using polyamide 9T resin, but does not suggest its seizure resistance performance.
The present invention has been made to solve the above-described problems, and provides a rolling bearing that does not cause damage such as seizure even under high temperature and high speed conditions in which a dm · n value is 60 × 10 ⁴ or more. With the goal.

The invention according to claim 1 is an outer ring having an outer ring raceway on an inner peripheral surface;
An inner ring having an inner ring raceway on the outer peripheral surface;
A plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be freely rollable;
A cage in which the rolling element is held between the outer ring and the inner ring and the material is molded of polyamide 9T resin;
And the dm · n value is 60 × 10 ⁴ or higher.
According to the present invention, the synthetic resin used for the cage is made by using a polyamide 9T resin having a relatively high glass transition temperature of about 125 ° C. as compared with the commonly used polyamide 66 resin and polyamide 46 resin. It is possible to suppress deformation of the cage during high-speed rotation and reduce heat generation due to sliding friction between the rolling elements and the cage.
According to the second aspect of the present invention, when glass fiber is contained in the cage material in an amount of 10 to 30% by mass, the cage stiffness is increased, and deformation of the cage is reduced even under conditions of higher temperature and higher speed rotation. However, the calorific value can be reduced, which is preferable.
Since the diameter of the pocket opening is 90 to 94% of the diameter of the rolling element in the cage, the invention according to claim 3 is a crown type cage used for a deep groove ball bearing, a double row angular ball bearing or the like. In this case, by setting the aperture of the pocket opening, it can be assembled to the bearing without any trouble.
The invention according to claim 4 is characterized in that the thickness of the cage on the side opposite to the pocket opening is at least 13% of the diameter of the rolling element. According to the present invention, since the crown type cage is opened to one side in the axial direction and the weight balance is biased, the pocket opening side is prevented from being greatly deformed to the outer diameter side by centrifugal force during high-speed rotation, and the rolling element and The amount of heat generated by the sliding friction of the cage can be reduced.

According to the present invention, a polyamide 9T resin is used as the material of the cage, so that it is possible to provide a rolling bearing that does not cause defects due to seizure even at a high speed rotation in which the dm · n value exceeds 60 × 10 ⁴ .
In addition, by containing 10-30% by mass of glass fiber in polyamide 9T resin, the rigidity of the cage is increased, the deformation of the cage is reduced even under conditions of higher temperature and high speed rotation, and the calorific value is reduced. Can do.
Further, the polyamide 9T resin has a very high melting point of 304 ° C., and can have extremely high heat resistance as compared with the most frequently used polyamide 66 resin (melting point 265 ° C.). In addition, the oil resistance and chemical resistance are superior to those of the polyamide 66 resin and the polyamide 46 resin, and the effect that it can be used under severer use conditions than in the past, for example, high temperature and in oil, is also achieved.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments of a rolling bearing according to the present invention will be given and described in detail below with reference to the accompanying drawings. 1 is a longitudinal sectional view of a deep groove ball bearing 10 according to a first embodiment of the present invention, FIG. 2 is a perspective view of the cage of FIG. 1, FIG. 3 is a longitudinal sectional view of the cage of FIG. Shows a cross-sectional view taken along line III-III in FIG.

  As shown in FIG. 1, the deep groove ball bearing 10 basically includes an outer ring 11 having an outer ring raceway 11a on an inner peripheral surface 11b, an inner ring 12 having an inner ring raceway 12a on an outer peripheral face 12b, an outer ring raceway 11a and an inner ring raceway 12a. Between a plurality of balls (rolling elements) 13 provided so as to be freely rollable in the circumferential direction, and between the inner peripheral surface 11b of the outer ring 11 and the outer peripheral surface 12b of the inner ring 12, It is composed of a crown-shaped cage (retainer) 20 formed of a polyamide 9T resin that is rotatably held.

  The deep groove ball bearing 10 uses a crown type cage 20 as shown in FIG. By using a polyamide 9T resin having a high glass transition temperature and excellent rigidity for the crown type cage 20, deformation can be suppressed even under high temperature and high speed rotation conditions. The polyamide 9T resin is also excellent in self-lubricating properties and low friction properties. Accordingly, the amount of heat generated by friction between the balls 13 and the crown-shaped cage 20 can be reduced, so that seizure does not occur, so that it can be operated for a long time. Furthermore, the effect can be enlarged more by using what contains 10-30 mass% of glass in the polyamide 9T resin.

The crown-shaped cage 20 is a ball provided between a claw portion 22 projecting from a plurality of locations to one side in the axial direction at equal intervals in the circumferential direction of the annular main portion 21 and a claw portion 22 adjacent in the circumferential direction. 13 is provided with a pocket opening 23 for storing 13. Here, the crown-shaped cage 20 holds the ball 13 by the interference between the claw portion 22 and the ball 13. Therefore, when the crown-shaped cage 20 is assembled to the deep groove ball bearing 10, it is necessary to avoid interference with the claw portion 22. For this reason, as shown in FIG. 4, when the diameter D _W of the pocket opening 23 is smaller than 90% of the diameter of the ball 13, there occurs a problem that the elastic piece 22 is broken. However, when the diameter D _W of the pocket opening 23 is greater than 94% of the diameter of the ball 13, since the crown type cage 20 could become detached during rotation, the diameter D _W of the pocket opening 23 of the ball 13 It is desirable to make it into the range of 90 to 94% of the diameter. Thus, since the diameter of the pocket opening 23 is set to 90 to 94% of the diameter of the ball 13, the crown-shaped cage 20 improves the assemblability to the deep groove ball bearing 10 and the crown shape during high-speed rotation. The retainer 20 can be prevented from coming off.

Here, the crown-shaped cage 20 has a structure in which the weight balance is biased by opening on one side in the axial direction. Therefore, when the wall thickness t of the annular main portion 21 on the opposite side of the pocket opening 23 is thin and the rigidity is insufficient, the opening side is greatly deformed to the outer shape side due to the influence of centrifugal force. As a result, heat generation due to friction between the balls 13 and the crown-shaped cage 20 increases. Further, when the deformation of the crown-shaped cage 20 becomes large, the crown-shaped cage 20 is in contact with the inner peripheral surface 11b of the outer ring 11 like the crown-shaped cage 81 shown by a broken line as shown in FIG. 7B. And may seize or dissolve. In order to prevent such a problem, it is desirable to secure the wall thickness t of the annular main portion 21 at least 13% of the diameter of the ball 13. 7A is a cross-sectional view of the main part of the ball bearing 70 using the iron cage 71, and FIG. 7B is the main part of the ball bearing 80 using the crown-shaped cage 81 formed of polyamide 66 resin or polyamide 46 resin. 7A and 7B, the same components as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted, and the following description is also made the same.
Thus, by securing the wall thickness t on the side opposite to the opening of the pocket opening 23 to at least 13% of the diameter of the ball 13, the rigidity of the annular main portion on the side opposite to the opening of the pocket is increased, and the pocket is generated by centrifugal force. It is possible to prevent the opening side from being greatly deformed to the outer diameter side and to suppress heat generation of the bearing.

On the other hand, a comparative test was performed between the deep groove ball bearing 10 of the present embodiment (the product of the present invention) sealed with grease as a lubricant and provided with non-contact type seals on both sides and the conventional product. The result is shown in FIG. In the conventional product, the outer ring temperature starts to increase rapidly when the dm · n value exceeds 60 to 70 × 10 ^4. However, the product of the present invention does not increase rapidly even if the dm · n value becomes 90 × 10 ^4. The effect of the present invention could be confirmed without being seen.

  5A and 5B are longitudinal sectional views of a double row deep groove ball bearing 30 and a double row angular ball bearing 40 according to the second embodiment of the present invention. 5A and 5B, reference numerals 31 and 32, 41 and 42 denote cages, and these cages 31 and 32, 41 and 42 are molded using a synthetic resin material, for example, polyamide 9T. .

  6A and 6B are longitudinal sectional views of single-row angular ball bearings 50 and 60 according to the third embodiment of the present invention. 6A and 6B, reference numerals 51 and 61 denote cages, and these cages 51 and 61 are molded using a synthetic resin material, for example, polyamide 9T.

It is a longitudinal cross-sectional view of the deep groove ball bearing which concerns on the 1st Embodiment of this invention. It is a perspective view of the crown type holder of FIG. It is a longitudinal cross-section of the crown type cage of FIG. It is sectional drawing of the III-III line of FIG. It is a longitudinal cross-sectional view of the double row deep groove ball bearing which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the double row angular contact ball bearing which concerns on the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the single row angular contact ball bearing with a large contact angle which concerns on the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view of the single row angular contact ball bearing with a small contact angle which concerns on the 3rd Embodiment of this invention. It is principal part sectional drawing of the deep groove ball bearing using an iron cage. It is principal part sectional drawing of a deep groove ball bearing about the crown type cage shape | molded by the polyamide 66 resin or the polyamide 46 resin. It is explanatory drawing which showed the seizure test result with this invention product and a conventional product (polyamide 66 resin product).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 70, 80 Deep groove ball bearing 11 Outer ring 11a Outer ring raceway 11b Outer ring inner peripheral surface 12 Inner ring 12a Inner ring raceway 12b Inner ring outer peripheral surface 13 Ball 20 Crown type retainer 21 Circular main part 22 Claw part 23 Pocket 30 Double row deep groove ball bearing 31, 41, 51, 61 Cage 40 Double row angular contact ball bearing 50, 60, Single row angular contact ball bearing

Claims (4)

An outer ring having an outer ring raceway on the inner peripheral surface;
An inner ring having an inner ring raceway on the outer peripheral surface;
A plurality of rolling elements provided between the outer ring raceway and the inner ring raceway so as to be freely rollable;
A cage in which the rolling element is held between the outer ring and the inner ring and the material is molded of polyamide 9T resin;
And a rolling bearing characterized by being used at a high speed rotation with a dm · n value of 60 × 10 ⁴ or more. The rolling bearing according to claim 1, wherein the cage material contains 10 to 30% by mass of glass fiber. 3. The rolling bearing according to claim 1, wherein a diameter of a pocket opening is 90 to 94% of the diameter of the rolling element in the cage. The rolling bearing according to any one of claims 1 to 3, wherein the thickness of the cage on the side opposite to the pocket opening is at least 13% of the diameter of the rolling element.

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