KR20040053689A - a bearing assembly - Google Patents

Abstract

Bearing assembly of the present invention disclosed is a central axis formed with a plurality of grooves; An upper bearing pressed into an upper portion of the central axis; A lower bearing press-fitted to the lower portion of the central axis away from the upper bearing; And an elastic body installed between the upper bearing and the lower bearing and configured to apply a preload to the upper and lower bearings. The plurality of grooves may include a first groove formed at a predetermined interval on an upper portion of the central axis, a smaller second groove and a third groove smaller than the second groove; And a fourth groove, a fifth groove smaller than the fifth groove, and a sixth groove smaller than the fifth groove formed at predetermined intervals below the central axis.

Description

Bearing assembly

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing assembly, and more particularly, to a bearing assembly that is easy to assemble a bearing on a central axis of a bearing assembly and has less thermal deformation.

In general, the bearing is a mechanical element that serves to rotate the shaft while holding the shaft of the rotating machine in a fixed position and supporting the load and the load on the shaft. In addition, there are various kinds of bearings such as rolling bearings and sliding bearings, and the bearings are selected and used according to the type of load applied to the bearings.

The type of load can be divided into two cases, which are applied in the axial direction and the case in which the load is applied in the axial direction. In particular, as the bearing assembly used for the load acting in the axial direction, as shown in FIG. ), The upper bearing 62, the lower bearing 64 and the coil spring 66.

As can be seen in the figure, the upper bearing 62 is press-fitted to the upper end of the central shaft 60, the lower bearing 64 is press-fitted to the lower end, and the upper bearing 62 and the lower bearing 64 are pressed. The coil spring 66 is inserted in between.

The upper and lower bearings 62 and 64 have an inner ring 67, an outer ring 68, and a plurality of balls 69 installed between the inner ring 97 and the outer ring 68, and the balls 69. It includes a retainer (not shown) to support the. The inner diameter of the upper and lower bearings 62 and 64 is smaller than the diameter of the central axis 60, and the central 60 axis is formed in a cylindrical shape and inserted between the upper and lower bearings 62 and 64. The coil spring 66 is preloaded with the inner ring 67 of the upper and lower bearings 62 and 64 to the spring.

The conventional bearing assembly is press-fitted while pressing the upper bearing 62 downward from the upper end of the central shaft 60, and in the state where the coil spring 66 is inserted, the lower bearing 64 The press is completed by pressing in the upward direction at the lower end.

2 is a view schematically showing the residual stress acting on the lower bearing of the bearing assembly of the prior art. The upper bearing also acts symmetrically with respect to the central axis 60.

Thus, the conventional bearing assembly, as shown in the figure, when pressing the lower bearing 64 to the central axis 60 in the direction of the arrow 72, the opposite of the pressing direction 72 of the lower bearing 64 The force F acts in the direction, and inside the central axis 66, the repulsive force 73 and the lower bearing push the lower bearing 64 out of the central axis 66, as shown in FIG. 2. The residual stress 75 which pushes the inner ring 67 of 64 downward remains.

In particular, the stress 73 is concentrated between the central axis 66 and the inner ring 67 of the lower bearing 64, and the stress is concentrated on the upper side of the lower bearing 64, as shown by the arrow 75 in the drawing, The inner ring 67 of the bearing 64 is pushed downward and the force to twist the central axis 60 is applied.

In the conventional bearing assembly, the upper and lower bearings 62 and 64 must be continuously pressurized and press-fitted from the upper and lower ends of the central axis 60 to the position where the upper and lower bearings 62 and 64 are installed. It is difficult to press-fit the upper and lower bearings 62 and 64 to the central axis 60, and excessive stress may be applied to the upper and lower bearings 62 and 64 and the central axis 60 to cause damage. have.

In addition, when the outer ring 68 of the central axis 60 or the upper and lower bearings 62 and 64 rotates at a high speed or heat is generated due to prolonged use, the central axis 60 and the upper and lower parts may be caused by excessive residual stress. Heat deformation occurs in the bearings 62 and 64, so that the positions of the upper and lower bearings 62 and 64 may be slightly changed, and the assembly accuracy of the bearing assembly may be degraded. It can be a fatal drawback in sensitive precision applications.

An object of the present invention devised to solve the problems of the prior art as described above is to provide a bearing assembly that is easy to assemble the bearing on the central axis, reducing damage to the central axis and the bearing.

In addition, another object of the present invention is to provide a bearing assembly with high assembly accuracy even in a field where a small amount of residual stress in the bearing and the central axis is less likely to cause thermal deformation during long time use, and high accuracy is required.

1 is a cross-sectional view showing a bearing assembly of the prior art,

Figure 2 is a schematic diagram schematically showing the residual stress acting on the bearing assembly of the prior art shown in Figure 1,

3 is a cross-sectional view showing an embodiment of a bearing assembly of the present invention;

FIG. 4 is a diagram illustrating a bare assembly of the present invention shown in FIG. 3, and schematically illustrates residual stress acting on a lower bearing.

<Description of the symbols for the main parts of the drawings>

14: Upper bearing 16: Lower bearing

17: Ball 18: Inner ring

19; outer ring 20; spring

25: center axis 36: upper drum

26 to 31: first to sixth groove

In order to achieve the object of the present invention as described above, the bearing assembly of the present invention, the central axis is formed with a plurality of grooves; An upper bearing pressed into an upper portion of the central axis; A lower bearing press-fitted to the lower portion of the central axis away from the upper bearing; And an elastic body installed between the upper bearing and the lower bearing and configured to apply a preload to the upper and lower bearings.

The plurality of grooves may include a first groove formed at a predetermined interval on an upper portion of the central axis, a smaller second groove and a third groove smaller than the second groove; And a fourth groove, a fifth groove smaller than the fifth groove, and a sixth groove smaller than the fifth groove formed at predetermined intervals below the central axis.

Here, the depth of the first groove and the fourth groove, the second groove and the fifth groove, the third groove and the sixth groove is preferably the same.

In addition, the shaft diameter of the portion from the first groove to the second groove of the central shaft is larger than the inner diameter of the upper bearing, the shaft diameter of the portion from the second groove to the third groove is smaller than the inner diameter of the upper bearing, Preferably, the shaft diameter from the third groove to the upper end of the central shaft is smaller than the shaft diameter of the portion from the second groove to the third groove.

The distance from the first groove to the second groove is greater than the distance from the second groove to the third groove, and the distance from the fourth groove to the fifth groove is greater than the distance from the fifth groove to the sixth groove. .

Herein, the distance from the first groove to the second groove is 6/11 to 2/3 of the distance from the first groove to the third groove, and the distance from the fourth groove to the fifth groove is from the fourth groove to the sixth groove. It is preferable that it is 6/11-2/3 of the distance to a groove.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view showing an embodiment of a bearing assembly of the present invention. As can be seen in the drawing, the bearing assembly of the present invention includes a central axis 25, an upper bearing 14, a lower bearing 16 and a spring 20.

The spring 20 is an embodiment of an elastic body having an elastic force, and may be applied to any elastic body capable of applying a preload in addition to the spring 20. In addition, the end of the spring 20 is inserted into the groove 35 formed in the outer ring 19 of the upper and lower bearings 14 and 16, and the outer ring 19 of the upper and lower bearings 14 and 16. Preload).

The center shaft 25 is formed with three grooves each at the top and the bottom. The first groove 26, the second groove 27 and the third groove 28 is formed in the upper portion, the fourth groove 29, the fifth groove 30 and the sixth groove 31 is formed in the lower portion Formed.

The first groove 26 is deeper than the second groove 27 and the second groove 27 is formed deeper than the third groove 28, and the fourth groove 29 is the fifth groove. Deeper than the 30 and the five groove 30 is formed deeper than the sixth groove (31). In particular, the first groove 26 and the fourth groove 29 are installed to the same depth, the second groove 27 and the fifth groove 30 to the same depth, the third groove 28 and the third groove It is preferable to install the six grooves 31 to the same depth.

The grooves 26 to 31 are formed at regular intervals, and as shown in FIG. 3, the distance from the first groove 26 to the second groove 27 is referred to as C, and the second groove ( When the distance from the first groove 26 to the third groove 28 is H, the distance from the first groove 26 to the third groove 28 is H, and the distance between the grooves is H> C> D. It is. In particular, it is preferable that C be in the range of 6H / 11 to 2H / 3.

In addition, the distance from the fourth groove 29 to the fifth groove 30 is B, the distance from the fifth groove 30 to the sixth groove 31 is A, and from the fourth groove 29 If the distance to the sixth groove 31 is F, the distance between the grooves is configured in order of F> B> A. In particular, it is preferable that B be in a range of 6F / 11 to 2F / 3.

In the present embodiment, the shaft diameter of the portion from the first groove 26 to the second groove 27 is configured to be slightly larger than the inner diameter of the upper bearing 16, the second groove 27 to the third The shaft diameter of the portion up to the groove 28 is configured to be slightly smaller than the inner diameter of the upper bearing 16, the shaft diameter of the upper portion K from the third groove 28 to the upper end of the central shaft 25 is It is configured to be smaller than the shaft diameter from the second groove 27 to the third groove 28.

In addition, the shaft diameter of the portion from the fourth groove 29 to the fifth groove 30 is configured to be slightly larger than the inner diameter of the lower bearing 14, the fifth groove (30) to the sixth groove (31) The shaft diameter of the part is configured to be slightly smaller than the inner diameter of the lower bearing 14, the shaft diameter (J) from the sixth groove 31 to the lower end of the central shaft is formed in the fifth groove (30) It is comprised smaller than the shaft diameter to the 6 groove | channel 31.

In particular, in the central axis 25, the configuration of the upper portion of the central shaft 25, the upper bearing 16 is press-fit and the lower portion of the central shaft 25, the press-fitted lower bearing 14 is the same. That is, the depths of the first grooves 26 and the fourth grooves 29 are the same, and the depths of the second grooves 27 and the fifth grooves 30 are the same, and the third grooves ( 28) and the sixth grooves 31 have the same depth. In addition, it was comprised so that J = K, A = D, B = C, F = H also in the distance and axial diameter between the grooves 26-31.

In the present embodiment, the upper and lower bearings 14 and 16 are rolling bearings, and include an inner ring 18 and an outer ring 19, a ball between them, and a retainer (not shown) holding them. However, the upper and lower bearings 14 and 16 may use various kinds of bearings in addition to rolling bearings.

The upper bearing 14 is press-fitted downward from the upper end of the central shaft 25 so that one end thereof reaches the first groove 26. In addition, the lower bearing 16 is installed such that one end thereof reaches upward from the lower end of the central shaft 25 to the fourth groove 29. The spring 20 is mounted between the upper bearing 14 and the lower bearing 16. The spring 20 preloads the outer ring 19 of the upper and lower bearings 14 and 16.

4 is a view schematically showing the stress applied to the bearing assembly of the present invention. Since the residual stress applied to the lower bearing 16 and the upper bearing 14 are the same shape, only the residual stress acting on the lower bearing 16 is shown in the drawings.

As can be seen in the drawing, the distance J from the lower end of the central shaft 25 to the sixth groove 31 is smaller than the inner diameter of the lower bearing 16, so the lower bearing 16 is inserted. Even if no stress occurs. However, since the distance A from the fifth groove 30 to the sixth groove 31 of the central shaft 25 is configured to be slightly smaller than the inner diameter of the lower bearing 16, the shaft diameter is slightly smaller. After the bearing 16 is pressed in, there is some residual stress, as shown.

Since the shaft diameter of the distance B from the fourth groove 29 to the fifth groove 30 of the central shaft 25 is larger than the inner diameter of the lower bearing 16, the portion is actually pressed. By applying a considerable pressure, the lower bearing 16 is press-fitted in the upward direction from the downward direction, so that not only the residual stress pushed out from the inside of the central shaft 25 but also the residual stress pushed downward in the opposite direction from the press-fitted direction are generated. do.

However, as can be seen in the drawing, the upper end of the lower bearing 16 is installed so as to be located in the fourth groove 29 so as to push down from the upper direction generated inside the central shaft 25 The residual stress is not canceled out. That is, in order for the stress to push downward in the upward direction as in the prior art, the upper end of the lower bearing 16 should be in contact with the central axis 25 (see FIG. 2). Since the groove 29 is formed, there is an effect of blocking the residual stress.

The same applies to the upper bearing 14. That is, since the lower end of the upper bearing 14 is installed in the first groove 26, there is no residual stress that pushes downward from the upper direction in the center shaft 25.

As described above, the bearing assembly of the present invention is configured to press and press the upper and lower bearings 14 and 16 to the central axis 25 while pressing the upper and lower bearings 14 and 16. Only the B and C portions of the central axis shown in Figure 3, the other parts are inserted without sliding, so that the residual stress acting on the upper and lower bearings (14, 16) can be minimized, Also, there is little fear that thermal deformation will occur.

In addition, by configuring the shaft diameter of the J, K, A, D portion (see Fig. 3) of the central axis 25 smaller than the inner diameter of the upper and lower bearings (14, 16), the upper and lower bearings (14) 16, easy to assemble, it is possible to reduce the damage of the bearing (14, 16) and the central axis (25) during assembly.

According to the embodiment of the bearing assembly of the present invention as described above, the assembly of the bearing is easy, it is possible to reduce the damage of the bearing and the central axis during assembly.

In addition, the present invention has a low residual stress on the bearing and the central axis, there is little risk of heat deformation due to high temperature even when using the bearing assembly of the present invention for a long time, and there is little fear that the assembly position of the upper and lower bearings change.

As described above and described with reference to a preferred embodiment for illustrating the principle of the present invention, the present invention is not limited to the configuration and operation as shown and described as such. Rather, those skilled in the art will appreciate that many modifications and variations of the present invention are possible without departing from the spirit and scope of the appended claims.

Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (7)

A central axis in which a plurality of grooves are formed; An upper bearing pressed into an upper portion of the central axis; A lower bearing press-fitted to the lower portion of the central axis away from the upper bearing; And an elastic body installed between the upper bearing and the lower bearing and configured to apply preload to the upper and lower bearings. The method of claim 1, The plurality of grooves may include a first groove formed at a predetermined interval on an upper portion of the central axis, a smaller second groove and a third groove smaller than the second groove; And a fourth groove, a fifth groove smaller than the fifth groove, and a sixth groove smaller than the fifth groove, formed at a predetermined interval in the lower portion of the central axis. The method of claim 2, The first and fourth grooves, the second groove and the fifth groove, the third and the sixth groove depth of the bearing assembly is the same. The method of claim 2, The shaft diameter of the portion from the first groove to the second groove of the central shaft is larger than the inner diameter of the upper bearing, and the shaft diameter of the portion from the second groove to the third groove is smaller than the inner diameter of the upper bearing. The shaft diameter from the three grooves to the upper end of the central shaft is smaller than the shaft diameter of the portion from the second groove to the third groove bearing assembly. The method of claim 2, The distance from the first groove to the second groove is greater than the distance from the second groove to the third groove, the distance from the fourth groove to the fifth groove is greater than the distance from the fifth groove to the sixth groove assembly. The method of claim 5, The distance from the first groove to the second groove is a bearing assembly, characterized in that 6/11 to 2/3 of the distance from the first groove to the third groove. The method of claim 5, And the distance from the fourth groove to the fifth groove is 6/11 to 2/3 of the distance from the fourth groove to the sixth groove.