JP7431519B2 - cross roller bearing - Google Patents

Description

The present invention relates to a cross-roller bearing in which rollers are arranged between an outer ring and an inner ring so that rollers are arranged in alternating directions of inclination in the circumferential direction.

Crossed roller bearings used in industrial robot reducers and the like are required to have stable characteristics such as high positioning accuracy, repeatability, and high moment rigidity.

For example, the cross roller bearing shown in Patent Document 1 has an outer ring and an inner ring that are integrally formed in an annular shape. A V-shaped raceway surface that opens inward is formed along the circumferential direction on the inner circumferential surface of the outer ring, and a V-shaped raceway surface that opens inward is formed on the outer circumferential surface of the inner ring, and a V-shaped raceway surface that opens outward is formed on the outer circumferential surface of the inner ring so as to face the raceway groove of the outer ring. A V-shaped raceway surface that opens toward the vehicle is formed along the circumferential direction. A large number of rollers are interposed between the raceway surfaces of the inner and outer rings so that the rotating axes of adjacent rollers are alternately orthogonal to each other.

Generally, the raceway surface of a cross-roller bearing is not crowned and consists only of a straight portion that is inclined at 45 degrees with respect to the axial direction of the bearing. Then, the rolling surface of the roller contacts this raceway surface and rolls (see paragraph 0012 of Patent Document 1, FIG. 1, etc.).

Patent No. 3739056

Since the cross roller bearing according to Patent Document 1 is not crowned, as shown in FIG. The rolling surface of the roller 24 can be contacted over the entire axial direction of the roller 24.

However, when a moment load is applied, as shown in FIG. The outer ring 2 in FIG. It shows a distribution in which the contact surface pressures S ₁ ′ and S ₂ ′ monotonically increase as the raceway surface position attached to the side goes from 100 to 1 or from the raceway surface position 1 attached to the inner ring 3 side to 100. Sometimes. At this time, there is a possibility that a problem may occur starting from a portion where the contact surface pressure is high (for example, the portion where the contact surface pressure is the maximum value S _m1 ′, S _m2 ′ in FIG. 8). Although it is conceivable to crown the roller 24 to make the distribution of contact surface pressure uniform, it is difficult to put it into practical use because the direction in which the roller 24 is installed needs to be controlled.

Therefore, an object of the present invention is to equalize the distribution of contact surface pressure acting on the raceway surface during moment loading.

In order to solve the above problems, the present invention provides an outer ring in which a V-groove-shaped outer ring raceway surface is formed on the inner diameter side, and a V-groove-shaped inner ring raceway surface facing the outer ring raceway surface is formed on the outer diameter side. a plurality of rollers arranged over the entire circumference in the circumferential direction so that the inclination angle alternately changes between the formed inner ring, the outer ring raceway surface, and the inner ring raceway surface, At least one of the outer ring raceway surface and the inner ring raceway surface has a groove bottom side deeper than an intermediate position in the radial direction from the groove shoulder to the groove bottom of each raceway surface, and a groove shoulder side shallower than the intermediate position. A cross roller bearing with crowning formed to vary the amount of drop was constructed.

In this way, the distribution of contact pressure acting on the raceway surface can be made uniform by setting an appropriate drop amount on the groove bottom side and groove shoulder side in response to the distribution of contact pressure on the raceway surface when a moment is loaded. can do. Thereby, it is possible to prevent the contact surface pressure from increasing locally, and to prevent the occurrence of problems originating from areas where the contact surface pressure is high.

In the above configuration, the crowning may be formed only on one side of the groove bottom side and the groove shoulder side, and the straight portion may be continuously provided on the other side. Alternatively, a straight portion in which the crowning is not formed is provided at the intermediate position of each raceway surface, and the crowning is continuously provided on both the groove bottom side and the groove shoulder side of the straight portion. It is also possible to do this.

In this way, high contact pressure locally generated at one end or both ends of the roller in the axial direction can be reduced while ensuring contact between the raceway surface and the roller in the straight portion.

In each of the above configurations, the crowning may be formed on both the outer ring raceway surface and the inner ring raceway surface.

In this way, it is possible to reduce the locally generated high contact surface pressure on both the outer ring and the inner ring, and it is possible to extend the life of the bearing.

In this invention, in the cross roller bearing, the crowning is formed so that the drop amount is different on the groove bottom side and the groove shoulder side of the raceway surface, so that the distribution of the contact surface pressure acting on the raceway surface during moment load is made uniform. Therefore, it is possible to prevent problems originating from areas where the contact surface pressure is high.

A partially cutaway front view of a cross roller bearing according to the present invention Cross-sectional view along line II-II in Figure 1 (first example) Cross-sectional view of the main parts of the cross roller bearing shown in Figure 1 (first example) Diagram showing an example of surface pressure distribution acting on the raceway surface Cross-sectional view of the main parts of a cross roller bearing (second example) Cross-sectional view of the main parts of a cross roller bearing (third example) Cross-sectional view of the main parts of a conventional cross roller bearing Diagram showing the surface pressure distribution acting on the raceway surface in a conventional cross roller bearing

An embodiment (first example) of a cross roller bearing 1 according to the present invention will be described with reference to the drawings. In the following description, a direction parallel to the rotational axis of the cross roller bearing 1 is referred to as an axial direction, a direction orthogonal to the rotational axis is referred to as a radial direction, and a direction along an arc centered on the rotational axis is referred to as a circumferential direction. As shown in FIGS. 1 and 2, this cross roller bearing 1 includes an outer ring 2, an inner ring 3 disposed coaxially with the outer ring 2 on the inner diameter side of the outer ring 2, and between the outer ring 2 and the inner ring 3. The main component is a plurality of intervening rollers 4. All of these components are made of steel.

On the inner diameter side of the outer ring 2, there is a V-groove-shaped outer raceway surface 5 that is substantially orthogonal to each other, and on the outer diameter side of the inner ring 3, there is a V-groove-shaped inner raceway surface 6 that is opposed to the outer ring raceway surface 5 and is substantially orthogonal to the outer ring raceway surface 5. , are formed respectively. In the following, the side deeper than the middle position in the radial direction from the groove shoulder to the groove bottom of each raceway surface 5, 6 is referred to as the groove bottom side (the side marked with a circled number 1 and a circled number 4 in FIG. 3). ), the shallow side is called the groove shoulder side (the side marked with circled numbers 2 and 3 in Figure 3).

As shown in FIG. 2, the groove bottom side and groove shoulder side of the outer ring raceway surface 5 and the groove bottom side and groove shoulder side of the inner ring raceway surface 6 have different shapes of raceway surfaces. That is, the groove shoulder sides of the inner and outer ring raceway surfaces 5 and 6 are not crowned, and the groove shoulder side raceway surfaces are composed of straight portions 7 and 8 that are inclined at 45 degrees with respect to the axial direction. . On the other hand, crownings 9 and 10 are provided on the groove bottom sides of the inner and outer ring raceway surfaces 5 and 6. In this way, by arranging the straight parts 7, 8 and the crownings 9, 10, the amount of drop on the groove shoulder side of the inner and outer ring raceway surfaces 5, 6 (the amount of drop between the rolling surface of the roller 4 and the inner and outer ring raceway surfaces 5, 6) is reduced. The size of the gap between The drop amount varies.

In addition, in FIG. 2 (the same applies to FIGS. 3, 5, and 6 showing cross-sectional views of the main parts of the cross roller bearing 1), the crownings 9 and 10 formed on the inner and outer ring raceway surfaces 5 and 6 are visually shown. Although the inclination angles of the crownings 9 and 10 are exaggerated in order to make them easier to see, the actual inclination angles are small (about 2 degrees, for example), and when a moment load is applied, the inclination angles of the crownings 9 and 10 are exaggerated. The rolling surface of the roller 4 can be in contact with the entire roller 4 in the axial direction.

The rollers 4 are arranged between the outer ring raceway surface 5 and the inner ring raceway surface 6 over the entire circumference in the circumferential direction so that the inclination angles of the rollers 4 adjacent to each other in the circumferential direction alternately change by 90 degrees. . The diameter of the roller 4 is slightly longer than its length in the rotation axis direction. For this reason, the end of the roller 4 in the rotational axis direction is located on the other side which is substantially orthogonal to one side of the V-shaped groove of the inner and outer raceway surfaces 5 and 6 on which the rolling surface of the roller 4 rolls. This roller 4 can be rolled smoothly without contacting the surface.

The rolling surface of the roller 4 is a cylindrical surface having a constant outer diameter throughout the axial direction, and is not crowned. Therefore, when installing the roller 4 between the inner and outer ring raceway surfaces 5 and 6, there is no need to manage the installation direction, and the installation work can be performed smoothly. Note that it is also possible to arrange a spacer between adjacent rollers 4 to ensure a gap of a predetermined size between the rollers 4.

As shown in FIG. 3, when crowning 9, 10 is applied only to the groove bottom sides of the inner and outer ring raceway surfaces 5, 6, and the groove shoulder sides are made into straight parts 7, 8, from the rolling surface of the roller 4. FIG. 4 shows an example of calculation results of the distribution of contact surface pressure acting on the inner and outer ring raceway surfaces 5 and 6. This calculation was performed using a model of the cross roller bearing 1 having an outer diameter of 85 mmΦ and an axial width of 18.5 mm. This figure divides the area from the groove bottom to the groove shoulder into 100 equal parts along the raceway surface, and shows the distribution of contact surface pressure in the area that is in contact with the roller 4 among the 100 equal parts of the raceway surface position. . Circled numbers 1 and 4 shown in FIGS. 3 and 4 correspond to the groove bottom side, and circled numbers 2 and 3 correspond to the groove shoulder side.

In this way, by applying crowning 9 and 10 only to the groove bottom sides of the inner and outer ring raceway surfaces 5 and 6, the contact surface pressure that tends to increase on the groove bottom side can be reduced (Fig. The magnitude relationship between the maximum contact surface pressures S _m1 ′, S _{m2 ′} shown in _FIG . 4 and the maximum contact _surface pressures S _m1 , S _m2 shown in _FIG. '), it is possible to equalize this contact surface pressure. This makes it possible to prevent problems originating from areas with high contact surface pressure. Furthermore, since a stable contact state between the raceway surface and the roller 4 can be ensured in the straight portions 7 and 8, the rotational stability of the cross roller bearing 1 can be improved.

Note that the distribution of contact surface pressure shown in Fig. 4 is just an example, and by changing the shape of the crownings 9 and 10 (size of inclination angle, length in the direction from the groove bottom to the groove shoulder, etc.) , the distribution can be changed as appropriate so that areas with high contact surface pressure do not occur.

Another embodiment (second example) of the cross roller bearing 1 according to the present invention is shown in FIG. The basic structure of this cross roller bearing 1 is the same as that of the first example, but the shapes of the inner and outer raceway surfaces 5 and 6 are different.

That is, in the cross roller bearing 1 according to the second example, the inner and outer ring raceway surfaces 5 and 6 are on the groove bottom side (the side marked with circled numbers 1 and 4 in FIG. 5) and the groove shoulder side ( The straight parts 7 and 8 formed in the middle part of the sides marked with circled numbers 2 and 3 in FIG. , 10a, and second crownings 9b, 10b connected to the groove shoulder sides of the straight parts 7, 8. The first crownings 9a, 10a and the second crownings 9b, 10b have different inclination angles and lengths in the direction from the groove bottom to the groove shoulder, and have different drop amounts.

In this way, by providing the crowning 9a, 9b, 10a, 10b on both the groove bottom side and the groove shoulder side of the inner and outer ring raceway surfaces 5, 6, the crowning height tends to increase as it comes into contact with both ends of the roller 4 in the axial direction. The contact surface pressure can be reduced and the contact surface pressure can be made uniform. Therefore, similarly to the cross roller bearing 1 according to the first example, it is possible to prevent problems originating from areas where the contact surface pressure is high. Furthermore, since a stable contact state between the raceway surface and the roller 4 can be ensured in the straight portions 7 and 8, the rotational stability of the cross roller bearing 1 can be improved.

Still another embodiment (third example) of the cross roller bearing 1 according to the present invention is shown in FIG. The basic configuration of this cross roller bearing 1 is the same as that of the first and second examples, but the shapes of the inner and outer raceway surfaces 5 and 6 are further different.

That is, in the cross roller bearing 1 according to the third example, the inner and outer ring raceway surfaces 5, 6 are formed on the groove bottom side (the side marked with circled numbers 1 and 4 in FIG. 6). It is comprised of one crowning 9a, 10a and a second crowning 9b, 10b formed on the groove shoulder side (the side marked with circled numbers 2 and 3 in FIG. 6). The first crownings 9a, 10a and the second crownings 9b, 10b have different inclination angles and lengths in the direction from the groove bottom to the groove shoulder, and have different drop amounts.

In this way, by applying the crowning 9a, 9b, 10a, 10b to both the groove bottom side and the groove shoulder side of the inner and outer ring raceway surfaces 5, 6, the roller 4 It is possible to reduce the contact surface pressure, which tends to increase due to contact with both axial ends of the contact surface, and to equalize this contact surface pressure. Therefore, similarly to the cross roller bearing 1 according to the first example, it is possible to prevent problems originating from areas where the contact surface pressure is high.

The cross roller bearing 1 shown in the above embodiment is merely an example, and as long as the problem of the present invention, which is to equalize the distribution of contact surface pressure acting on the raceway surface during moment load, can be solved, Appropriate changes in shape, arrangement, material, etc. are permitted.

In the embodiment described above, the V-groove-shaped inner and outer raceway surfaces 5, 6 are divided into a plurality of portions having different inclination angles (straight portions 7, 8 and crowning 9, 10 in the first example, straight portion 7, crowning 9, 10 in the second example, 8 and two crownings 9a, 9b, 10a, 10b; in the third example, two crownings 9a, 9b, 10a, 10b), but the crowning is continuous over the entire inner and outer raceway surfaces 5, 6. It can also be configured by 9. Further, in the above embodiment, the V-groove inner and outer ring raceway surfaces 5 and 6 are shaped symmetrically with respect to the center of the groove, but they can also be shaped asymmetrically. Further, the crowning 9 can be applied only to one side of the outer ring raceway surface 5 or the inner ring raceway surface 6.

1 Cross roller bearing 2 Outer ring 3 Inner ring 4 Roller 5 Outer ring raceway surface 6 Inner ring raceway surface 7, 8 Straight portions 9, 10 Crownings 9a, 10a First crownings 9b, 10b Second crownings

Claims (4)

an outer ring (2) having a V-groove-shaped outer ring raceway surface (5) formed on the inner diameter side;
an inner ring (3) in which a V-groove inner ring raceway surface (6) facing the outer ring raceway surface (5) is formed on the outer diameter side;
a plurality of rollers (4) arranged around the entire circumferential direction between the outer ring raceway surface (5) and the inner ring raceway surface (6) so that the inclination angle alternately changes;
has
The outer ring raceway surface (5) and the inner ring raceway surface (6) have a drop amount on the groove bottom side that is deeper than an intermediate position in the radial direction from the groove shoulder to the groove bottom of each of the raceway surfaces (5, 6). , a cross roller bearing in which the crowning (9, 10) is formed to be larger than the drop amount on the groove shoulder side shallower than the intermediate position. The crowning (9, 10) is formed only on one side of the groove bottom side and the groove shoulder side, and the straight portion (7, 8) is continuously provided on the other side. Cross roller bearing. Straight portions (7, 8) in which the crowning (9, 10) is not formed are provided at the intermediate positions of the raceway surfaces (5, 6), and the groove bottoms of the straight portions (7, 8) The cross roller bearing according to claim 1, wherein the crownings (9, 10) are continuous on both the side and the groove shoulder side. The cross roller bearing according to any one of claims 1 to 3, wherein the crowning (9, 10) is formed on both the outer ring raceway surface (5) and the inner ring raceway surface (6).

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