JP3042121B2 - Precision bearing spindle device and assembly method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The precision bearing spindle device and the method of assembling the same according to the present invention are used for supporting the main shaft of a precision lathe without any axial deflection.

[0002]

2. Description of the Related Art As shown in FIG. 3, a rotary shaft 1 such as a main shaft of a precision lathe is rotatably supported inside a housing 2 through a plurality of rolling bearings 3, 3. I have. Rolling bearings 3, 3 include, in addition to radial loads, such as angular ball bearings, deep groove ball bearings, tapered roller bearings,
Use a structure that can support the load in the axial direction.

However, the rotating shaft 1 rotatably supported inside the housing 2 by the above-described rolling bearings 3 and 3 swings in the axial direction (left and right directions in FIG. 3) with rotation (reciprocation). Move). That is, the rotating shaft 1
When the rotating shaft 1 is rotated in a state in which the high-precision displacement meter 4 is opposed to the center of the end surface 1a of the end surface 1a, as shown in FIG. It changes as one cycle L. Detected by the displacement meter 4 in this manner,
The amount of displacement δ of the rotating shaft 1 in the axial direction is very small in the order of μm or less.

On the other hand, with the recent improvement in the accuracy of manufacturing equipment and the like, the end face of a metal material is finished in sub-μm units using an ultra-hard tool such as a diamond tool. In the case of performing such high-precision machining, even if the displacement amount δ of the rotating shaft 1 is extremely small in μm units or less, it cannot be ignored in terms of machining accuracy.

The inventors of the present invention have studied the cause of the run-out in the axial direction of the rotary shaft 1 which adversely affects the processing accuracy. As a result, the raceway surfaces of the races constituting the rolling bearings 3, 3 have been studied. It turned out that it was due to the distortion.

That is, the outer raceway 6 and the inner race 7 on the inner peripheral surface of the outer race 5
Each of the rolling bearings 3, 3 configured by rotatably mounting a plurality of rolling elements 9, 9 between the inner ring raceway 8 on the outer peripheral surface.
Is provided with a plurality of rolling elements 9, 9 between the outer raceway 6 and the inner raceway 8 in order to support not only the radial (diameter) load but also the axial (axial) load without play.
Are pressed in the radial direction and the axial direction.
That is, when assembling the rolling bearings 3, the components 5, 7, 9 are elastically deformed to elastically press the outer raceway 6 and the inner raceway 8 against the plurality of rolling elements 9, 9. A so-called preload is applied.

However, the outer raceway 6 and the inner raceway 8
The shape in the circumferential direction does not become a perfect circle due to an unavoidable manufacturing error, and it is unavoidable that the shape is slightly, but slightly non-circular, such as elliptical or triangular. Outer ring 5 and inner ring 7 having non-circular outer ring track 6 and inner ring track 8 in this manner
When the two members 5 and 7 are relatively rotated by concentrically combining the two, the axial distance between the outer raceway 6 and the inner raceway 8 changes. Thus, when the axial distance between the outer raceway 6 and the inner raceway 8 changes, the force for pressing the rolling elements 9, 9 elastically held between the raceways 6, 8 changes, As a reaction, the outer ring 5 and the inner ring 7 are displaced in the axial direction.

[0008] For example, as shown exaggeratedly in FIG. 5, when the outer ring raceway 6 (broken line a) and the inner ring raceway 8 (solid line b) are all at the oval, the same and the outer ring raceway 6 and the inner ring raceway 8 As shown in FIG. 7A, when the positional relationship is such that the long axis and the short axis of each other coincide with each other, the preload amount of the rolling elements 9 becomes appropriate, and the outer ring 5 and the inner ring 7 There is no deviation. However, when the long axis of the inner raceway 8 and the short axis of the outer raceway 6 are aligned as shown in FIG. Exist in the vicinity,
The preload amount of some rolling elements becomes excessive, and the outer ring 5 and the inner ring 7 tend to shift in the axial direction.

The state shown in FIG. 5 (A) and the state shown in FIG. 5 (B) are repeatedly generated each time the inner ring 7 makes one rotation inside the outer ring 5, and therefore the rotation fitted and supported inside the inner ring 7. Axis 1
Swings in the axial direction. FIG. 6 shows the amount of displacement of the rotating shaft 1 in the axial direction caused by such a cause. In the case of an angular ball bearing having an inner diameter of 70 mm and a contact angle of 15 degrees, the axial runout amount when the elliptical amount of the outer ring raceway and the elliptical amount of the inner raceway are equal is shown. The elliptic amount related to the difference between the major axis and the minor axis, and the vertical axis represents the axial displacement of the rotating shaft 1 respectively.

As is apparent from FIG. 6, by precisely finishing the outer raceway 6 and the inner raceway 8 and bringing the raceways 6, 8 closer to a perfect circle, the axial displacement of the rotary shaft 1 can be reduced. However, it is difficult to finish each of the tracks 6 and 8 in a perfect circle, which is not preferable because it causes an increase in manufacturing cost.

The precision bearing spindle device of the present invention has been invented in view of such circumstances.

[0012]

All of the precision bearing spindle devices of the present invention, like the conventional precision bearing spindle device, have a plurality of inner races between the outer raceway on the inner peripheral surface of the outer race and the inner race raceway on the outer peripheral surface of the inner race. The rolling element is provided so that it can roll freely, by a rolling bearing that is capable of supporting the load in the axial direction and the radial direction, inside the housing having a cylindrical inner peripheral surface, a shaft having a cylindrical outer peripheral surface, It is configured to be supported for relative rotation.

In particular, in the precision bearing spindle device of the present invention ,
In the precision bearing spindle device according to the first aspect of the present invention , the rolling bearings have directions of contact angles opposite to each other.
A plurality of rolling bearings, and each of the rolling bearings is driven by these two raceways due to the undulation of the outer raceway and the inner raceway.
The phase with respect to the rotation direction of the part where the distance between the roads becomes narrower
By arranging them in a state where they match each other, the outer ring and inner ring
The present invention is characterized in that the axial vibration generated due to the relative rotation with the above is offset . A precision bearing according to claim 2.
In the spindle device, each other as the above-mentioned rolling bearing
When two or more devices with the same contact angle
In addition, each rolling bearing is
In the area where the distance between these two orbits is
The phases in the rotation direction are shifted 90 degrees from each other.
Caused by the relative rotation between the outer ring and the inner ring
It is characterized by offsetting axial vibration. Change
The precision bearing spindle device according to claims 3 and 4,
In the assembling method, according to claim 1 or claim 2 described above.
To configure the described precision bearing spindle device,
Due to the undulation of the inner and outer raceways
Phase in the direction of rotation of the part where the distance between
After the measurement, the phases are matched with each other or shifted by 90 degrees
By combining them with the outer ring and inner ring,
Axial run-out caused by relative rotation is offset.

[0014]

In the case of the precision bearing spindle device and the assembling method of the present invention configured as described above, any one of the plurality of rolling bearings is displaced in any direction, so that the shaft is moved. At the same time that the shaft tends to be displaced in one direction, the other rolling bearing is displaced in another direction, so that the shaft tends to be displaced in another direction. As a result, forces in directions opposite to each other are applied to the shaft, so that the shaft is not displaced in the axial direction, or even if displaced, the displacement is extremely small, which is practically negligible.

[0015]

FIG. 1 shows an embodiment of the present invention corresponding to the first and third aspects . Rotating shaft 1 inside housing 2
Are rotatably supported by two rolling bearings 3,3. Each rolling bearing 3, 3 which is an angular ball bearing
Is formed by mounting a plurality of rolling elements 9 and 9 between the outer raceway 6 on the inner peripheral surface of the outer race 5 and the inner raceway 8 on the outer peripheral surface of the inner race 7 so as to be freely rotatable. In the combined state, the outer rings 5, 5 are fitted inside the housing 2, the inner rings 7, 7 are fitted outside the rotating shaft 1, and a preload is applied.

Outer rings 5, 5 constituting each rolling bearing 3, 3
The shape of the inner peripheral surface of the outer ring raceways 6, 6 in the circumferential direction is exaggerated in FIG.
As shown by a, although it is elliptical, both outer raceways 6,
6 have the same phase. The shape of the inner races 7, 8 in the circumferential direction of the inner races 8, 8 on the outer peripheral surfaces of the inner races 7, 7 is also exaggerated in FIG.
As shown by, the inner raceways 8 have the same phase as each other. Each orbit in this way
In order to make the phases of 6 and 8 coincide with each other,
Precise measurement of the shape of 8
The wheels 5, 5 are mounted on the housing 2, the inner rings 7, 7 are mounted on the shaft 1, and
Fix each.

As the outer raceway 6 and the inner raceway 8 are elliptical as described above, the inner races 7, 7 of the rolling bearings 3, 3 are rotated as the rotating shaft 1 rotates. Based on the change of the preload amount as described above, there is a tendency to be displaced in the axial direction.
However, since the two rolling bearings 3 and 3 are combined in the back as described above, the inner rings 7 and 7 of the two rolling bearings 3 and 3 are provided.
Are opposite to each other. In addition, since the phases of the outer raceways 6, 6 and the inner raceways 8, 8 coincide with each other, forces applied in the axial direction of the inner races 8, 8 with the rotation of the rotating shaft 1 are generated at the same timing. Will do.

As a result, the forces applied in the axial direction of the inner races 8 and 8 cancel each other, and no axial force acts on the rotating shaft 1 on which the inner races 8 are fitted. The rotation shaft 1 does not displace in the axial direction,
Even in the case of displacement, the displacement amount is extremely small, which can be ignored in practical use.

FIG. 2 shows a combination example in which the displacement of the rotary shaft 1 can be suppressed, including the case of the above-described embodiment. FIG. 2A has already been described.
In addition, these all show the thing using the angular contact ball bearing as the rolling bearing 3. The arrow in each figure is
The direction in which the inner rings 7, 7 are pressed when the shaft is rotated in one direction from the illustrated state is shown.

FIG. 2B is a view similar to FIG.
3 shows an embodiment in which a pair of rolling bearings 3 are combined in a so-called front combination. In the case of this embodiment, the function is the same as that shown in FIG. 2A, except that the pressing direction of the inner rings 7, 7 is opposite to that in FIG. 2A.

FIG. 2C also shows a request similar to FIG.
Items corresponding to items 1 and 3, two rolling bearings 3 , 3,
In addition to combining them in parallel with each other,
Pairs are combined back to back. The function is the same as that of FIG. 2A except that a total of four rolling bearings 3 are used.

FIG. 2 (D) is also similar to FIG.
Corresponding to the items 1 and 3, the outer rings 5, 5 constituting a pair of rolling bearings 3, 3 combined with each other by a back combination, the phases of the outer ring raceways 6, 6 on the inner peripheral surface, the inner ring 7,
The phases of the inner ring raceways 8, 8 on the outer peripheral surface 7 are shifted from each other by 90 degrees. Even in the case of such a configuration, a force for displacing the inner rings 7, 7 in the axial direction with the rotation of the rotating shaft 1 is generated in the opposite direction at the same timing. The shaft 1 is prevented from being displaced in the axial direction.

FIG. 2E also shows a request similar to FIG.
A pair of rolling bearings 3, 3
Are combined in a so-called front combination. In the case of this embodiment, the pressing direction of the inner rings 7, 7 is shown in FIG.
The function is the same as that shown in FIG. 2D except that the direction is opposite to that of FIG.

FIG. 2F also shows a request similar to FIG.
Items corresponding to items 1 and 3, two rolling bearings 3 , 3,
In addition to combining them in parallel with each other,
Pairs are combined back to back. In this example, the phases of the inner two outer raceways and the inner raceway are shifted by 90 degrees with respect to the two outer bearings,
The function is the same as that of FIG. 2D.

FIGS. 2G and 2H correspond to claims 2 and 4.
This shows an example in which two rolling bearings 3 are combined in parallel with each other. (G) shows an example in which the phases of the inner raceways 8 and 8 are shifted from each other by 90 degrees, and (H) shows an example in which the phases of the outer raceways 6 and 6 are shifted from each other by 90 degrees. FIG. 2I corresponds to all of claims 1 to 4.
, Two rolling bearings 3, 3 combined in parallel with each other
At the same time
It is a combination. In this example, the outer 2
Phase of outer ring raceway of inner two bearings for one bearing
Are shifted 90 degrees and combined back to back
In each set, the function is the same as that of FIG.
You.

When the precision bearing spindle device is actually incorporated in a precision lathe or the like, it is preferable that the phases of the outer raceways 6, 6 coincide with each other. This is because the inner rings 7, 7 are often fitted around the rotary shaft 1 by interference fit. Therefore, if the outer peripheral surface of the rotary shaft 1 is not a perfect circle, the inner rings 7, 7 fixed to the rotary shaft 1 are fitted. The inner ring raceways 8, 8 of the surface
Is non-circular, and usually has the same phase, in accordance with the outer peripheral surface of the. On the other hand, since there is often a very small gap between the outer peripheral surfaces of the outer rings 5, 5 and the inner peripheral surface of the housing 2, the inner peripheral surface of the housing 2 is non-circular. However, it is unlikely that the outer raceways 6, 6 become non-circular in accordance with this, and it is desirable to form the outer raceways 6, 6 in advance with the phases thereof being matched.

Although the above description has been made with reference to an angular contact ball bearing, a deep groove type ball bearing, such as an angular type, is used in a state where an axial load is supported, and a tapered roller bearing is also applicable. Can be similarly configured.

[Brief description of the drawings]

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

FIG. 2 is a partial cross-sectional view showing nine examples of a combination state.

FIG. 3 is a sectional view showing an example of a precision bearing spindle device to which the present invention is applied.

FIG. 4 is a diagram showing a run-out of the rotary shaft in the axial direction.

FIGS. 5A and 5B are a cross-sectional view and a diagram for explaining the cause of axial deflection.

FIG. 6 is a diagram showing an elliptical amount and a magnitude of an axial displacement amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating shaft 1a End surface 2 Housing 3 Rolling bearing 4 Displacement meter 5 Outer ring 6 Outer ring track 7 Inner ring 8 Inner ring track 9 Rolling element

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16C 19/54 F16C 25/08 F16C 35/06

Claims (4)

(57) [Claims] 1. A plurality of rolling elements are provided between an outer raceway on an inner peripheral surface of an outer race and an inner raceway on an outer peripheral surface of an inner race so as to roll freely.
A precision bearing in which a shaft having a cylindrical outer peripheral surface is relatively rotatably supported inside a housing having a cylindrical inner peripheral surface by a rolling bearing capable of supporting axial and radial loads. In the spindle device,
The contact angles of the rolling bearings are opposite to each other.
The provided with a plurality, each rolling bearing due to the undulation of the outer ring raceway and inner ring raceway of both track each other's
The phase in the rotation direction of the narrower part is
By arranging them in a state of matching, the relative position between the outer ring and the inner ring
A precision bearing spindle device characterized by offsetting axial run- out caused by rotation . A plurality of rolling elements are rotatably provided between an outer raceway on an inner peripheral surface of the outer race and an inner raceway on the outer peripheral surface of the inner race;
A precision bearing in which a shaft having a cylindrical outer peripheral surface is relatively rotatably supported inside a housing having a cylindrical inner peripheral surface by a rolling bearing capable of supporting axial and radial loads. In the spindle device,
A plurality of rolling bearings having the same contact angle direction are provided as the above-mentioned rolling bearings, and each rolling bearing is provided with a rotating direction in a portion where the interval between these two raceways becomes narrow due to the undulation of the outer raceway and the inner raceway. A precision bearing spindle device characterized in that by disposing the phases with respect to each other by 90 degrees, axial run-out caused by relative rotation between the outer ring and the inner ring is offset. 3. A plurality of rolling elements are rotatably provided between an outer raceway on an inner peripheral surface of an outer race and an inner raceway on an outer peripheral surface of an inner race.
A precision bearing in which a shaft having a cylindrical outer peripheral surface is relatively rotatably supported inside a housing having a cylindrical inner peripheral surface by a rolling bearing capable of supporting axial and radial loads. In the method of assembling the spindle device, a plurality of rolling bearings having opposite contact angle directions are prepared as the rolling bearings, and each of these rolling bearings is
After previously measuring the phase in the rotational direction of the portion where the interval between these two tracks becomes narrower due to the undulation of the outer ring track and the inner ring track, by combining these phases in a state where they are aligned with each other, the outer ring and the outer ring are combined. A method of assembling a precision bearing spindle device, wherein an axial run-out caused by relative rotation with an inner ring is offset. 4. A plurality of rolling elements are rotatably provided between an outer raceway on an inner peripheral surface of an outer race and an inner raceway on an outer peripheral surface of the inner race,
A precision bearing in which a shaft having a cylindrical outer peripheral surface is relatively rotatably supported inside a housing having a cylindrical inner peripheral surface by a rolling bearing capable of supporting axial and radial loads. In the method of assembling the spindle device, a plurality of the rolling bearings having the same contact angle direction are prepared as the above-mentioned rolling bearings, and each of these rolling bearings is provided with the two raceways due to the undulation of the outer raceway and the inner raceway. After measuring in advance the phase in the direction of rotation of the part where the distance between them becomes smaller, the phases are shifted by 90 degrees from each other, thereby offsetting the axial runout caused by the relative rotation between the outer ring and the inner ring. A method for assembling a precision bearing spindle device.