JPH01264725A - Engagement of shaft bearing inner ring with shaft - Google Patents

Abstract

PURPOSE:To facilitate manufacture of a shaft at a high precision by forming the shaft to be of the same diameter for its whole length, selecting the inner diameters of rolling bearing inner rings to be large or small within the range of specific tolerances, the larger one being for running fit, and the smaller one for tight fit, and inserting them into the shaft. CONSTITUTION:A shaft 5 is manufactured to be of the same diameter for its whole length without having a step. For the inner diameters of rolling bearing inner rings, among specific tolerance range for the shaft diameters, bearings 6 having an inner ring inner diameter 6a of a small specific tolerance, and bearings 8 having a inner ring inner diameter 8a of a large tolerance are selected, and the bearings 6 are engaged to the shaft 5 for tight fit, while the bearings 8 are engaged for running fit. In this constitution, the shaft 5 can be manufactured having the same outer diameter wholly, thereby precision can be good.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of fitting an inner ring of a bearing to an extremely high-precision shaft, and particularly to facilitate machining of the shaft, increase precision, improve rotation accuracy, and improve bearing life. The present invention relates to a method for fitting an inner ring of a bearing, which can extend the length of the shaft and significantly reduce the cost of the shaft.

Conventional technology Conventionally, precision motors, -i motors, OA (office automation) equipment, video tape recorders, and other AV (
When installing multiple (for example, a pair of) rolling bearings of the same size on one shaft, such as those used as high-precision bearings for audio/visual equipment, etc., the inner ring of one rolling bearing should be fitted with a clearance fit to the shaft. The inner ring of the other rolling bearing is fitted onto the shaft with a tight fit.

The reason why one of the pair of rolling bearings mounted on one shaft is mounted on the shaft by a clearance fit and the other one by a tight fit is mainly due to the following reasons.

(1) When a temperature change occurs between the shaft and the rolling bearing (including the housing), expansion or contraction occurs in the longitudinal direction of the shaft, causing a change in the thrust preload of the rolling bearing, and the rotation of the shaft and rolling bearing. It is necessary to prevent this from having an adverse effect on the shaft, and for this purpose it is necessary to absorb expansion and contraction in the longitudinal direction of the shaft at one rolling bearing.

(2) If one inner ring of a rolling bearing is fixed to the shaft with a tight fit so that the amount of protrusion of the shaft from the rolling bearing is constant, if both rolling bearings are fitted with a tight fit, it will be difficult to measure the distance between them and the housing. Therefore, it is necessary to relieve the dimensional error in one of the rolling bearings.

(3) When multiple rolling bearings are mounted on one shaft and their outer rings are fixed to the housing, if the shaft between the rolling bearings expands and stretches due to temperature rise due to rotation, both rolling bearings will If the shaft is fitted with a tight fit, buckling load will be applied to the shaft and it will bend.
It is necessary to release the elongation of the shaft at one rolling bearing.

(4) It is necessary to facilitate the assembly work by fixing one rolling bearing to one shaft with a clearance fit and attaching the other rolling bearing with a clearance fit.

(5) Conventionally, the inner ring of a rolling bearing was glued to the shaft with adhesive, but by fixing one of the rolling bearings with a tight fit, the number of steps required for gluing can be reduced, and the inner ring of the rolling bearing can be glued inside the bearing. Although it is possible to prevent the agent from entering, in this case, it is necessary to provide the other rolling bearing with a clearance fit for the above-mentioned reason.

However, conventionally, as shown in FIG. 6, when mounting a pair of rolling bearings 2.3 on one shaft 1, the inner ring 2a of one rolling bearing 2 is fitted into the shaft 1 with a clearance fit, and the inner ring 2a of the other rolling bearing 2 is In order to fit the inner ring 3a of one rolling bearing 3 to the shaft 1 with a tight fit, as shown in the figure, the inner diameters of the inner rings 2a and 3a of the rolling bearing 2.3 are the same size, and the diameter of the shaft 1 is Partially changed small diameter part 1a
A large diameter portion 1b is formed, a step 1c is provided, and a small diameter portion 1a is formed.
and the diameter of the large diameter portion 1b is 2/1000 to 15/10.
They adopted a method of making a difference within a range of 0.00 m.

However, due to recent advances in technology, the accuracy of axis 1 has become
The requirements are so high that they cannot be met by the JIS standards, and in particular, precise diameters are required to have an accuracy on the order of 5/10000 tm. It is technically extremely difficult to partially change the diameter of such ultra-high precision shaft 1, and this step machining inevitably reduces the accuracy of shaft 1, making the machining process complicated. This method requires a large number of man-hours, resulting in poor production efficiency and high costs, and has drawbacks such as shortening the life of the rolling bearing.

Purpose The present invention was made in order to eliminate the drawbacks of the prior art described above, and its purpose is to fit the inner ring of a rolling bearing to an extremely high precision shaft. We focused on the fact that in rolling bearings manufactured based on JIS standards, the variation in the dimensional tolerance of the inner ring of each product is considerably larger than the finishing accuracy of the shaft, as the diameter tolerance is too strict. The shaft is manufactured to have the same diameter over its entire length without any steps with different diameters, and the rolling bearings are selected within the standard tolerance for the inner diameter of the inner ring, or those with the inner diameter differing within a predetermined range are manufactured. Then, by fitting a rolling bearing with a large inner diameter for clearance fit on one part of the shaft, and a rolling bearing for tight fit with a small inner diameter on the other part of the shaft, the shaft can be made with high precision. The purpose is to provide a shaft that is easier to manufacture and has higher precision, thereby improving the rotation accuracy of various precision equipment such as video tape recorders, and extending the life of rolling bearings. Another purpose is to simplify the shaft machining process, improve production efficiency, and significantly reduce the cost of high-precision shafts.

Configuration: In short, the method of the present invention provides a method for fitting the inner ring of a rolling bearing to a plurality of parts of a shaft manufactured with extremely high dimensional accuracy, roundness, and other precision. In a method of fitting an inner ring of a bearing in which an inner ring to be fitted to another part is fitted with a clearance fit, and an inner ring which is fitted to another part is fitted with a tight fit, the shaft is manufactured to have the same diameter over the entire length without providing a step with a different diameter, Rolling bearings are selected within standard tolerances for the inner diameter of the inner ring, and a rolling bearing with a large inner diameter for clearance fit is used for part of the shaft, and a rolling bearing for tight fit with a small inner diameter is used for the other part of the shaft. This is characterized in that the bearings are fitted into each other.

Furthermore, in the method of the present invention, when the inner ring of a rolling bearing is fitted to a plurality of parts of a shaft manufactured with extremely high dimensional accuracy, roundness, and other precision, the inner ring of the rolling bearing is fitted to a part of the shaft. In a bearing inner ring fitting method in which the inner ring is fitted with a clearance fit, and the inner ring fitted with another part is fitted with a tight fit, the shaft is manufactured to have the same diameter over its entire length without providing a step with a different diameter, Bearings are manufactured with inner rings with different inner diameters within a predetermined range, and a rolling bearing with a large inner diameter is used for a part of the shaft, and a rolling bearing with a larger inner diameter is used for the other part of the shaft. This is characterized by the fact that small rolling bearings for tight fit are fitted into each bearing.

The present invention will be explained below based on embodiments shown in the drawings. 1st
In the figure, the shaft 5 is formed to have the same diameter over its entire length, and is rotatably mounted on the machine frame 4 by rolling bearings 6.8 mounted near both ends 5a and 5b.

One rolling bearing 6 consists of an inner ring 6a, an outer ring 6b, and a plurality of balls 6c, and the inner diameter of the inner ring 6a is made slightly smaller than the diameter of the shaft 5.

Therefore, the difference in diameter between the shaft 5 and the inner ring 6a is a shimmy 5C, and the rolling bearing 6 is press-fitted (slim fit) so that it does not move in the axial direction of the shaft 5, that is, in the directions of arrows A and B.

Similarly to the rolling bearing 6, the other rolling bearing 8 is also
It consists of an inner ring 8a, an outer ring 8b, and a plurality of balls 8c, but since the inner diameter of the inner ring 8a is made slightly larger than the diameter of the shaft 5, there is a gap between the shaft 5 and the inner ring 8a. A very small gap 5d is formed by the difference in diameter between them. That is, the rolling bearing 8 is loosely fitted to the shaft 5, so that the shaft 5 can move in the directions of arrows A and B relative to the inner ring 8a.

The outer rings 6b, 8b of the rolling bearings 6, 8 are press-fitted into the machine frame 4, and a plurality of balls 6c, 8c are attached to the inner rings 6a, 8.
The shaft 5 is mounted without any play between the shaft 5 and the shaft 5, and the shaft 5 is rotatably supported by its rotation.

Next, a method of fitting the shaft 5 and the rolling bearing 6.8 will be described in detail. In the illustrated extremely high-precision rolling bearing, if the diameter of the shaft 5 is, for example, 5 mm, the permissible tolerance range is approximately ±2/1000 m. The high precision axis 5
A method of obtaining a rolling bearing 6.8 having inner rings 6a and 8a with inner diameters such that one side is a tight fit and the other side is a loose fit is as follows: There is a method to select from among the multiple rolling bearings.

That is, the inner diameter tolerance range of a JIS standard class 7 rolling bearing with an inner diameter of 5 fl is 12/1000 tm, that is, it is manufactured within a range of 6/100 (1+m) on the plus side and minus side with respect to the center dimension.

In addition, when examining the inner diameter dimensions of a large number of rolling bearings, the variation in the inner diameter dimensions is a normal distribution with approximately the same number of rolling bearings with inner diameter dimensions on the plus side and rolling bearings with inner diameter dimensions on the minus side with respect to the center dimension. It is known that

Therefore, we measured the inner diameters of multiple rolling bearings, and selected a rolling bearing with an inner ring whose inner diameter was 2/1000 m to 6/1000 m larger than the shaft diameter 5. Also from 2/1000n
If a rolling bearing with an inner ring having an inner diameter smaller by 6/1000 m is selected as the rolling bearing 6 for tight fit, approximately the same number of rolling bearings for loose fit and tight fit will be obtained.

To explain the above relationship in more detail with reference to FIG. 3, the hatched area on the lower right side of FIG. The upwardly hatched portions represent groups 10, 11, 12, 13, 14 of rolling bearings having inner rings with varying inner diameters as indicated by arrows 10a, lla, 12a, 13a, 14a, respectively.

A group of rolling bearings 10 is 6/100 smaller than the target size.
It is a group of rolling bearings that have an inner ring with a large inner diameter in the range of 0 to 4/1000 m, and a group of rolling bearings 1
1 is 4/1000 to 2/1000m than the target size
It is a collection of rolling bearings that have an inner ring with a larger inner diameter.

Similarly, the rolling bearing groups 12, 13, and 14 are each 2/1000 to -2/1000 m relative to the target dimensions.

2/1000~-4/1000m, -4/1000~6
This is a collection of rolling bearings having an inner ring with an inner diameter in the relationship of /1000M100O.

Also, the diameter of the shaft group 9 is 2/1000 to -2/10
There is a variation of 00 cranes. Here, one shaft 5 is arbitrarily selected from the group 9 of the shafts, and a group 10 of rolling bearings is selected.
When one rolling bearing 8 is arbitrarily selected from 11 and combined, the diameter of the shaft 5 is always smaller than the inner diameter of the inner ring of the rolling bearing 8.

That is, if the shaft 5 and the rolling bearing 8 are arbitrarily selected and combined from the shaft group 9 and the rolling bearing group 10° 11, the relationship between the shaft 5 and the inner ring of the rolling bearing 8 is created as shown at the left end of FIG. A gap 5d is always created between them, and a tight fit is obtained. □Similarly, if a shaft 5 and a rolling bearing 6 are arbitrarily selected and combined from the shaft group 9 and the rolling bearing group 13.14, the diameter of the shaft 5 is always larger than the inner diameter of the inner ring 6a of the rolling bearing 6. A large shimmy 5c is produced as shown at the right end in FIG. 4, and a snug fit is obtained.

Note that when the shafts 5 of the shaft group 9 and the rolling bearings 15 of the rolling bearing group 12 are combined, the range of variation in each dimension overlaps from 2/1000 to -2/1000 m, so there is a clearance fit. It is not certain whether there will be a tight fit, and depending on the individual combination of the selected shaft 5 and the rolling bearing 15, it is not known whether the fit will be at the left end, right end, or center in FIG. The combination is
Not used in this invention.

Function The present invention is constructed as described above, and its function will be explained below. There is no need to provide a step on the outer diameter of the shaft 5 over its entire length, and it is sufficient to manufacture the shaft 5 with exactly the same outer diameter, so there are no limitations on the manufacturing method, and it is possible to choose from various manufacturing methods in terms of accuracy and cost. There is a greater degree of freedom in selecting the most suitable method.For example, it becomes possible to manufacture the shaft in large quantities at low cost, fully automatically using a centerless cylindrical grinder.

On the other hand, for the rolling bearings 6 and 8, rather than specially manufacturing extremely high-precision rolling bearings,
It is possible to obtain a rolling bearing suitable for fitting simply by selecting from rolling bearings that are produced in large quantities and at low cost within the S standard tolerance range and are commercially available.

In this way, by using an extremely highly accurate and inexpensive shaft 5 and rolling bearings 6, 8, one of which is a tight fit and the other one is a clearance fit, an extremely highly accurate rotating shaft mechanism is provided at a low cost. I can do it.

In FIG. 1, when the temperature changes due to ambient temperature or heat generation inside the device, the machine frame 4 and shaft 5 that hold the rolling bearings 6.8 expand and contract in the directions of arrows A and B. Even if the materials of the machine frame 4 and the shaft 5 have the same coefficient of thermal expansion, it takes time for heat to transfer, and the temperatures of the cough machine frame 4 and the shaft 5 are different, so the amount of expansion and contraction of these is different. . Moreover, when the thermal expansion coefficients of the machine frame 4 and the shaft 5 are different, the difference in the amount of expansion and contraction becomes even more significant.

Here, one end 5a of the shaft 5 and the rolling bearing 6 have an inner ring 6a.
Since it is a tight fit, its relative position does not move, but the other end 5b is connected to the rolling bearing 8 and its inner ring 8.
A is assumed to be a clearance fit, and there is a clearance 5d, so the difference in the amount of expansion and contraction between the shaft 5 and the machine frame 4 is easily absorbed by a relative movement between one end 5b of the shaft 5 and the inner ring 8a of the rolling bearing 8. Therefore, there is no change in the thrust preload of the rolling bearings 6 and 8, and the shaft 5 is always kept in smooth rotation.

Effect The present invention has the advantage that when the inner ring of a rolling bearing is fitted to an extremely high-precision shaft as described above, the dimensional tolerance of the diameter of the shaft is too strict. Focusing on the fact that the variation within the dimensional tolerance of the inner diameter of the inner ring of each product is considerably larger than the finishing accuracy of the shaft, we manufactured the shaft to have the same diameter over the entire length without providing a step with a different diameter. Rolling bearings are selected within standard tolerances for the inner diameter of the inner ring, or those with different inner diameters within a predetermined range are manufactured, and a rolling bearing with a large inner diameter for clearance fit is installed on a part of the shaft. Since the other part of the shaft is fitted with a rolling bearing with a small inner diameter for a tight fit, it is easy to manufacture the shaft with high precision, and a shaft with higher precision can be provided. This has the effect of improving the rotation accuracy of various precision instruments such as video tape recorders, and also improving the life of rolling bearings. Furthermore, since the machining process of the shaft can be simplified, production efficiency can be improved and the cost of highly accurate shafts can be significantly reduced.

[Brief explanation of the drawing]

Figures 1 to 4 relate to embodiments of the present invention, with Figure 1 being a vertical cross-sectional view showing the fitted state of a shaft supported by a rolling bearing on the machine frame, and Figure 2 being a longitudinal sectional view showing the fitted state of the shaft supported by a rolling bearing on the machine frame. A perspective view showing a rolling bearing. Fig. 3 is an explanatory diagram showing the range of variation in the outer diameter of the shaft and the inner diameter of the inner ring of the rolling bearing. Fig. 4 is a longitudinal section showing three types of fitted states of the shaft and the rolling bearing. FIG. 5 is a perspective view showing a conventional rolling bearing mounted on a shaft having a stepped diameter. IC is a step, 5 is a shaft, 6 is a rolling bearing that is tightly fitted to the shaft, 6a and 8a are inner rings, and 8 is a rolling bearing that is tightly fitted to the shaft. Patent applicant Ogawa Seisakusho Co., Ltd. Representative Patent attorney 1) Kazuo Figure 5

Claims (1)

[Claims] 1. When the inner ring of a rolling bearing is fitted to multiple parts of a shaft manufactured with extremely high dimensional accuracy, roundness, and other precision, the inner ring of the rolling bearing is fitted to a part of the shaft. In a method of fitting an inner ring of a bearing in which an inner ring to be fitted to another part is fitted with a clearance fit, and an inner ring which is fitted to another part is fitted with a tight fit, the shaft is manufactured to have the same diameter over the entire length without providing a step with a different diameter, Rolling bearings are selected within standard tolerances for the inner diameter of the inner ring, and a rolling bearing with a large inner diameter for clearance fit is used for part of the shaft, and a rolling bearing for tight fit with a small inner diameter is used for the other part of the shaft. A method of fitting a bearing inner ring to a shaft, characterized by fitting the bearings to each other. 2. When the inner rings of a rolling bearing are fitted to multiple parts of a shaft manufactured with extremely high dimensional accuracy, roundness, and other precision, the inner rings fitted to the parts of the shaft must be fitted with a clearance fit, etc. In a bearing inner ring fitting method in which the inner ring that fits into a part of the bearing is fitted with a tight fit, the shaft is manufactured to have the same diameter over its entire length without providing a step with a different diameter, and the inner ring of the rolling bearing is The shafts are manufactured with inner diameters that differ within a predetermined range, and one part of the shaft is equipped with a rolling bearing with a large inner diameter for clearance fit, and the other part of the shaft is equipped with a rolling bearing with a small inner diameter for tight fit. A method of fitting a bearing inner ring to a shaft, characterized by fitting the bearings to each other.