JPH1113755A - Rolling bearing device applied with pre-load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily apply desired pre-load to a plurality of balls by applying a thrust load in the direction of approaching both inner rings constituting a pair of ball bearings to each other to at least one stopper ring of first and second stopper rings while measuring resonant frequency, and approaching both stopper rings to each other. SOLUTION: The middle part of a shaft member 2 is rotatably supported with a rolling bearing device constituted of a pair of ball bearings 1a, 1a arranged on two positions separated from each other in the axial direction through a ring opening spacer 19, and both ends of the bearing device is fixed with a pair of stopper rings 7, 7. When such bearing device is assembled, while measuring the resonant frequency of the rolling bearing device, a thrust load in the direction of approaching both inner rings 4a, 4a of a pair of the ball bearings 1a to each other is applied to the one stopper ring 7 of a pair of the stopper rings 7, 7. Hence by approaching both the inner rings 4a, 4a to each other, desired pre-load is applied to a plurality of balls 5 between the inner rings 4a and the outer rings 6a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various precision rotating parts such as a spindle motor, a rotary actuator, and a rotary encoder for a video tape recorder (VTR), a hard disk drive (HDD), and a laser beam printer (LBP). The present invention relates to a rolling bearing device which is incorporated to support a shaft which is a rotating part.

[0002]

2. Description of the Related Art Ball bearings are used to support shafts such as spindles of VTRs and HDDs. Ball bearings used in such precision rotating parts include whirling motion (movement in a direction perpendicular to the shaft). ) And a predetermined preload must be applied in order to prevent axial runout. For this reason, conventionally, a pair of independent ball bearings (deep groove type or angular type) has been used,
BACKGROUND ART A rolling bearing device that applies a predetermined preload by pressing an inner ring or an outer ring that constitutes a pair of ball bearings to the opposite side in the axial direction is known.

FIG. 5 shows an example of such a rolling bearing device. In this rolling bearing device, a pair of deep groove type (angular type) ball bearings 1 and 1 are provided between an outer peripheral surface of a shaft member 2 and an inner peripheral surface of a housing 3. A predetermined preload is applied to the plurality of balls 5, 5 constituting the two ball bearings 1, by pressing the pair of inner rings 4, 4 constituting the first ball bearing 1 in directions approaching each other.

[0004] For this reason, the inner races 4, 4 constituting the above-mentioned double ball bearings 1, 1 are respectively fixed at two positions separated from each other in the axial direction of a shaft member 2 on which the inner races are fitted. It is press-fitted and fixed with a margin. Then, at least one of the inner races 4, 4 is slightly moved in the axial direction (the left-right direction in FIG. 5) so that the inner races 4, 4 are brought closer to each other. The inner rings 4 and 4 are fixed to the shaft member 2 while applying a predetermined preload to the shaft member 2. The opposite end faces of the outer races 6 constituting the two ball bearings 1 abut against a step formed on the inner peripheral surface of the housing 3 in which the outer races 6 are fitted. These outer rings 6, 6 are kept away from each other.

Although not shown, the shaft member is a so-called stepped shaft in which a small diameter portion and a large diameter portion are connected by a step portion.
A rolling bearing device in which a pair of ball bearings internally fitted in a housing is externally fitted to a small diameter portion of the stepped shaft is also conventionally known. In the case of a rolling bearing having such a structure, by applying a load directed to the step portion to the ball bearing on the side opposite to the step portion of the two ball bearings, a plurality of ball bearings constituting the two ball bearings are formed. A predetermined preload is applied to the ball. Therefore, of the two ball bearings, an axially outer side of the ball bearing opposite to the stepped portion (the axially outer side refers to a side of the two ball bearings that does not face each other. The same applies in this specification). An annular retaining ring is press-fitted into the portion with a predetermined interference, and the two ball bearings are clamped between the retaining ring and the stepped portion.

Further, each inner ring and the small diameter portion forming the double ball bearing, and each outer ring and the housing forming the double ball bearing are each fitted with a small gap. By applying a thrust load to the retaining ring in a direction toward the step portion and fixing the retaining ring to the small diameter portion, a predetermined preload amount is applied to a plurality of balls constituting the double ball bearing. ing.

[0007]

However, in the case of the above-described conventional rolling bearing devices to which a preload is applied, there are the following problems, respectively. First, in the case of the above-described first example of the conventional structure, in order to prevent each of the ball bearings 1 and 1 from coming off from the shaft member 2, the load of each of the ball bearings 1 and 1 with respect to this shaft member 2 (the load applied to the shaft member 2). On the other hand, the thrust load required for the inner rings 4 and 4 to move) must be equal to or more than a certain value required by design. Therefore, the fitting portion between the inner races 4 and 4 and the shaft member 2 needs to have a relatively large interference.

As described above, when the interference between the inner races 4, 4 constituting the respective ball bearings 1, 1 and the shaft member 2 is increased, the diameter of the inner races 4, 4 is elastically increased. Therefore, the radial gap itself of each of the ball bearings 1 and 1 becomes smaller, and conversely, the variation of the radial gap becomes larger. For this reason, it is necessary to use the ball bearings 1 and 1 having a large radial gap in anticipation of a reduction in the radial gap. The variation in the radial clearance of each of the ball bearings 1 and 1 is calculated by adding the variation in the radial clearance inherent in the ball bearings 1 and 1 to the variation in the radial clearance based on the increased interference. In addition, it becomes even bigger. Therefore, assuming that the rigidity of the obtained rolling bearing device is constant as conventionally known, the double ball bearing 1,
In the method of applying a thrust load to the rolling bearing device while measuring the resonance frequency of the rolling bearing device including 1, and applying a predetermined preload to the rolling bearing device, the preload varies under the influence of each of the above variations, Variations in the rotational torque of the obtained rolling bearing device become large, and it becomes difficult to realize a rolling bearing device having stable performance.

In the case of the above-mentioned second example of the conventional structure, the retaining ring provided for applying the thrust load is fixed by bonding or press-fitting. When the retaining ring is fixed by bonding, if the degreasing performed in advance on the bonded portion of the stepped shaft is insufficient, there is a possibility that a preload may be released due to defective bonding after bonding.
In addition, there is a problem in that the yield is reduced due to the excess adhesive being protruded, and the heat cycle resistance of the bonded portion is deteriorated. The degreasing work as described above is troublesome, and it is not easy to check the adhesive strength. On the other hand, when the retaining ring is fixed by press fitting, it is difficult to accurately grasp the preload applied to the rolling bearing device. The load applied to the retaining ring includes a load consumed for applying a preload to the rolling bearing device and a load consumed for preventing the rolling bearing from coming off. The load consumed for applying the preload is much smaller than the load consumed for preventing the falling-off. Therefore, it is difficult to accurately control and set the preload applied to the rolling bearing device by separating the load consumed for applying the preload from the load consumed for preventing the coming off. Further, in the case of the structure of the second example, since the shaft is a stepped shaft, the manufacturing operation is troublesome, and the manufacturing cost is undesirably increased. The rolling bearing device to which the preload is applied according to the present invention is intended to solve any of the above-mentioned problems.

[0010]

SUMMARY OF THE INVENTION A preloaded rolling bearing device according to the present invention is sandwiched between axial end surfaces of a pair of ball bearings and two outer rings constituting the pair of ball bearings. Outer ring spacer and the axially outer portion of the pair of ball bearings,
In a state where both inner rings constituting the pair of ball bearings are sandwiched, the shaft member is press-fitted with a predetermined interference.
Each of the first and second retaining rings is formed in an annular shape. The above-mentioned pair of ball bearings may have a clearance fit with a minute gap or an interference fit with a minute interference margin at two positions that are separated from each other in the axial direction on the outer peripheral surface of the shaft member. A pair of inner races having outer raceways on their respective inner peripheral surfaces, and a pair of inner races having outer raceways on their respective inner peripheral surfaces; A plurality of balls are provided between the inner raceway and the outer raceway. Then, while measuring the resonance frequency, a thrust load is applied to at least one of the first and second retaining rings in a direction to bring the two inner rings constituting the pair of ball bearings closer to each other. By bringing the first and second retaining rings closer to each other, a desired preload is applied to the plurality of balls.

When the outer diameter of the shaft member is d,
The size of the gap between the shaft member and the inner ring for the clearance fit or the interference fit is from + 0.002d (gap fit) to
It is preferable to regulate to about -0.002d (tight fit). Further, the size of the interference for the interference fit between the shaft member and the first and second retaining rings is determined by setting the outer diameter of the shaft member to d,
The outer diameter of each retaining ring is 1.3d to 1.8d, and the width is 0.25d
0.002d to 0.005d
It is preferable to regulate to the extent.

[0012]

In the case of the rolling bearing device provided with the preload according to the present invention having the above-described structure, it is incorporated in various precision rotating parts to support the shaft member, which is the rotating part, similarly to the above-mentioned conventional structure. In particular, in the case of the rolling bearing device to which the preload is applied according to the present invention, the shaft member is fixed to a pair of the ball bearings in a state where the inner rings constituting the pair of ball bearings are sandwiched by the axially outer portions thereof. And the annular first and second retaining rings are press-fitted respectively. Accordingly, the inner ring and the shaft member that constitute the pair of ball bearings are not fixed by press fitting, and may be a gap fit having a minute gap or an interference fit having a minute interference.
The inner ring does not move with respect to the shaft member.

As a result, the diameter of each of the inner rings does not expand elastically, the radial gap of the rolling bearing does not decrease, and the variation in the radial gap does not increase. Therefore, it is not necessary to use a rolling bearing having a large radial clearance. Further, since the variation in the radial gap is reduced by the absence of a large interference, a thrust load is applied between the first and second retaining rings while measuring the resonance frequency of the ball bearing device, and this rolling is performed. Even with the method of applying a predetermined preload to the bearing device, the variation in the rotational torque of the obtained rolling bearing device does not increase.

Further, since the above-described ball bearings and the shaft member are not fixed by bonding, problems caused by bonding, such as insufficient bonding, labor for degreasing work, confirmation of bonding strength, excess adhesive protruding, and the formation of a bonding portion. The problem of deterioration in heat cycle resistance is eliminated. In addition, the preloaded rolling bearing device of the present invention can be manufactured relatively inexpensively because it is only necessary to combine general-purpose components having a general structure with a straight shaft that is not a stepped shaft. The degree of freedom also increases.

[0015]

FIG. 1 shows a first embodiment of the present invention. The rolling bearing device to which a preload is applied according to the present invention includes a shaft member 2, a pair of ball bearings 1 a, 1 a disposed at two positions axially separated from each other in an intermediate portion of the shaft member 2, It comprises a pair of annular retaining rings 7, 7 corresponding to the first and second retaining rings, and an outer ring spacer 19. The pair of ball bearings 1a, 1a are externally fitted at two positions separated from each other in the axial direction on the outer peripheral surface of the shaft member 2, respectively.
A pair of inner races 4a, 4a having inner races 8, 8 on their respective outer peripheral surfaces, and arranged in a state of facing the outer peripheral surfaces of both inner races 4a, 4a, and outer races 9, 9 on their respective inner peripheral surfaces
A pair of outer races 6a, 6a having
8 and a plurality of balls 5 provided between the outer raceways 9 respectively. Said inner races 4a, fitting between 4a and the shaft member 2, 0.2% of the outer diameter d ₂ of the shaft member 2
(0.002d ₂ ) or a gap fitting having a small gap of 0.2% or less (0.002d ₂ ) of the outer diameter d ₂ of the shaft member 2.
₂ ) An interference fit with the following minute interferences is used.

A cylindrical outer race spacer 19 is sandwiched between the axially opposed end faces of the outer races 6a, 6a. Then, the pair of retaining rings 7, 7 are provided on the axially outer portions of the ball bearings 1 a, 1 a by a part of the shaft member 2, and the inner rings 4 a,
4a, a predetermined interference D (0.002d ₂ ≦ D ≦ 0.005d ₂₎ which is equal to or more than the minute interference and equal to or less than 0.5% of the outer diameter d ₂ of the shaft member 2 in a state where the pinch 4a is held. ). Each of these retaining rings 7, 7 is made of a material having sufficient strength, such as bearing steel such as SUJ2, like the shaft member 2 described above. In addition, the above-mentioned interference D was set to 0.
Given that restricts the range of 002d ₂ ~0.005d _2, the outer diameter d ₇ of the respective stop ring 7, 7 (1.3 to 1.
8) restricted to a range of d _2, also the width W ₇ (0.25 to
0.5) for regulating the range of d _2.

The rolling bearing device of the present invention thus configured measures the resonance frequency of the rolling bearing device including the pair of ball bearings 1a, 1a while measuring the resonance frequency of the pair of retaining rings 7, 7. To one retaining ring 7 (or both retaining rings 7, 7)
Both inner rings 4a, 4 forming the pair of ball bearings 1a, 1a
A desired preload is applied to the plurality of balls 5, 5 by bringing the two inner rings 4a, 4a closer to each other while applying a thrust load in a direction to bring the balls a closer to each other.

FIG. 2 shows an example of a method for applying a preload to the rolling bearing device of the present embodiment. The shaft member 2 is attached to the holder 11.
, And one of the pair of ball bearings 1a, 1a (left side in FIG. 2).
The vibrator 12 is abutted against one end face (the left end face in FIG. 2) of the outer ring 6a that constitutes a, and vibration is applied to the rolling bearing device via the outer ring 6a. Further, the vibration sensor 13 is brought into contact with the other end face (the right end face in FIG. 2) of the outer ring 6a constituting the other (right side in FIG. 2) ball bearing 1a of the pair of ball bearings 1a, 1a. In addition, the resonance frequency of the rolling bearing device can be freely measured.

The resonance frequency of the rolling bearing device detected by the vibration sensor 13 is input to a controller 16 via an amplifier 14 and a frequency converter 15 for performing a fast Fourier transform (FFT). I have. The controller 16 includes the pair of ball bearings 1a, 1
The pushing device 17 for pushing the inner ring 4a, which constitutes one of the ball bearings 1a (right side in FIG. 2) 1a, through the retaining ring 7 is controlled. In the case of the illustrated example, the pushing device 1
7, a hydraulic cylinder is used. Controller 16
By controlling the amount or pressure of the pressurized oil fed into the pushing device 17, the force of the pushing arm 18 of the pushing device 17 pressing the retaining ring 7 is adjusted.

When an appropriate amount of preload is applied to the rolling bearing device of the present invention, pressure oil is fed into the pushing device 17 while measuring the resonance frequency of the rolling bearing device by the vibration sensor 13. Then, the retaining ring 7 is press-fitted and fixed to the shaft member 2 while the inner ring 4 a is pressed by the pushing arm 18 via the retaining ring 7. When the resonance frequency substantially matches the preset frequency, the feeding of the pressurized oil to the pushing device 17 is stopped, and the press-fitting operation is completed. In this state, a desired preload is applied to the rolling bearing device.

The fact that there is a certain relationship between the resonance frequency of the rolling bearing device and the preload is described, for example, in Japanese Patent Publication No. 2-61700.
As described in Japanese Unexamined Patent Publication (Kokai) No. HEI 10-301, it is conventionally known.
Therefore, it has the same configuration as the rolling bearing device to be manufactured,
In addition, if the resonance frequency of the rolling bearing device to which the desired preload is applied is measured in advance, and the measured value is set in the controller 16, in a state where the preload of the rolling bearing device reaches a desired value, The supply of the pressure oil to the pushing device 17 is stopped. The operation of measuring the resonance frequency of the rolling bearing device to which a desired preload has been applied only needs to be performed once.

The preloaded rolling bearing device of the present invention configured as described above can apply a desired preload to the plurality of balls 5, 5 without causing the above-described problem of the conventional structure. That is, a predetermined tightening is performed on the shaft member 2 in a state where the inner rings 4a, 4a constituting the pair of ball bearings 1a, 1a are sandwiched between the pair of ball bearings 1a, 1a in the axially outer portion. A pair of annular retaining rings 7, 7 are press-fitted with a margin. Thus, the pair of ball bearings 1
Each of the inner races 4a, 4a constituting the shaft members 2a, 1a and the shaft member 2 are not fixed by press-fitting, and may be a gap fit having a minute gap or an interference fit having a minute interference. The inner rings 4a, 4a do not shift with respect to the shaft member 2. Therefore, even if the retaining rings 7, 7 are pressed into the shaft member 2 with a predetermined interference, the radial clearances of the ball bearings 1a, 1a are not affected. As a result, the diameters of the inner rings 4a, 4a are hardly elastically widened, and the radial clearances of the ball bearings 1a, 1a are hardly reduced. Therefore, there is no need to use a large radial gap for the ball bearings 1a and 1a. Further, the variation in the radial gap becomes smaller because there is no large interference between each ball bearing 1a, 1a and the shaft member 2. Therefore, the preload of the rolling bearing does not change due to the variation of the radial gap, and a desired preload is applied by a method of applying a predetermined preload to the rolling bearing device while measuring a resonance frequency generated in the rolling bearing device. As a result, the variation in the rotational torque of the rolling bearing device does not increase. In addition, each of the inner rings 4a, 4a
Is not fixed by press fitting, the shape of the fitting surface of the shaft member 2 with the inner rings 4a, 4a is transferred to the inner ring raceways 8, 8 of the inner rings 4a, 4a. And vibration characteristics are not degraded. Further, the width W ₇ (FIG. 1) of each snap ring 7, 7 to externally secured by interference fit to the shaft member 2, (0.25 to 0.5) d ₂
The degree and the width W _4a of the inner rings 4a, 4a of the ball bearings 1a, 1a can be small. Therefore, each of the retaining rings 7,
Even if the shaft member 7 is fitted around the shaft member 2 by interference fit, the shaft member 2 is hardly distorted such as bending.

Further, since the fixing of the inner rings 4a, 4a to the shaft member 2 is not performed by bonding, problems caused by bonding, such as labor for degreasing work, confirmation of bonding strength, protrusion of excess adhesive, The problem of deterioration of the heat cycle resistance of the bonded portion is eliminated. In addition, the rolling bearing device of the present invention can be manufactured relatively inexpensively and has a high degree of design freedom because it is only necessary to combine general-purpose components having a general structure with a straight shaft that is not a stepped shaft. .

FIG. 3 shows a second embodiment of the present invention.
An example is shown. In the case of this example, a pair of ball bearings 1a, 1
The two outer races 6a, 6a constituting a are internally fitted in the cylindrical housing 3. An outer ring spacer is integrally provided on the inner peripheral surface of the housing 3. That is, this housing 3
Is formed in a cylindrical shape as a whole, and a small-diameter portion 10 is formed in a portion of the inner peripheral surface near the axial center. This small diameter part 10
Corresponds to the outer ring spacer, and the small diameter portion 10 is sandwiched between mutually facing axial end faces of the outer rings 6a, 6a. The outer races 6a and 6a are fitted to the housing 3 by a clearance fit having a small clearance or a close fit having a small interference.

In the case of the present embodiment constructed as described above, the outer races 6a, 6a constituting the pair of ball bearings 1a, 1a are fitted in the housing 3 with a clearance fit with a small clearance or a small interference. The outer races 6a, 6a do not move with respect to the housing 3 even if they are internally fitted as a loose interference fit. Therefore, the outer races 6a, 6a do not shrink with the assembly of the rolling bearing device, the radial gap between the rolling bearings 1a, 1a does not decrease, and the variation in the radial gap increases. Disappears.
Other configurations and operations are the same as those in the first example described above, and therefore, the same reference numerals are given to the same parts, and the duplicate description will be omitted.

FIG. 4 shows a third embodiment of the present invention.
An example is shown. In the case of this example, the inner peripheral surface of the housing 3a is a single cylindrical surface, and the small diameter portion 10 (FIG. 3) as in the structure of the above-described second example is not formed. Instead, a cylindrical outer ring spacer 19 is sandwiched between mutually facing axial end faces of the outer rings 6a, 6a constituting the pair of ball bearings 1a, 1a. The outer race spacer 19 is press-fitted to the inner peripheral surface of the housing 3a. Other configurations and operations are
Since this is the same as the above-described second example, the same parts are denoted by the same reference numerals, and redundant description will be omitted.

In the case of the rolling bearing device to which the preload is applied according to the present invention, the retaining rings 7 corresponding to the first and second retaining rings,
The shape and size of 7 need not necessarily be the same.
However, it is advantageous from the viewpoint of reducing the manufacturing cost that the retaining rings 7, 7 have the same shape and the same size so that the parts can be shared. Also, each of these retaining rings 7, 7
The shape and dimensions of are determined by design in consideration of materials, stress balance, circumferential stress and the like.

[0028]

As described above, the preloaded rolling bearing device according to the present invention is constructed and operated, so that the problem caused by the adhesive fixation or the change in the radial clearance of the ball bearing constituting the rolling bearing device is obtained. In addition to eliminating the problems caused by the above, an appropriate preload can be applied while reducing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a method of applying a desired preload to the rolling bearing device of FIG.

FIG. 3 is a sectional view showing a second example of the embodiment of the present invention.

FIG. 4 is a sectional view showing the third example.

FIG. 5 is a sectional view showing an example of a conventional structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Ball bearing 2 Shaft member 3, 3a Housing 4, 4a Inner ring 5 Ball 6, 6a Outer ring 7 Retaining ring 8 Inner ring track 9 Outer ring track 10 Small diameter section 11 Holder 12 Exciter 13 Vibration sensor 14 Amplifier 15 Frequency converter 16 controller 17 pushing device 18 pushing arm 19 outer ring spacer

Claims (1)

[Claims] An outer peripheral surface of a shaft member which is externally fitted at two positions spaced apart from each other in the axial direction by a clearance fit having a minute gap or an interference fit having a minute interference; A pair of inner races each having an inner raceway on an outer peripheral surface thereof, a pair of outer races disposed to face the outer peripheral surfaces of the two inner races, and having an outer raceway on each inner peripheral surface; A pair of ball bearings each including a plurality of balls provided between the respective outer ring raceways, and a cylindrical cylindrical member sandwiched between axial end surfaces of both outer rings constituting the pair of ball bearings. The shaft member was press-fitted into the outer ring spacer and the axially outer portion of the pair of ball bearings while holding the two inner rings constituting the pair of ball bearings together with a predetermined interference. , With first and second retaining rings each formed in an annular shape While measuring the resonance frequency, a thrust load is applied to at least one of the first and second retaining rings in a direction to bring the inner rings constituting the pair of ball bearings closer to each other. A rolling bearing device in which the first and second retaining rings are brought close to each other to apply a desired preload to the plurality of balls, and the preload is applied.