JP7516270B2 - Cross roller bearing - Google Patents

Description

This invention relates to a cross roller bearing in which rollers are arranged between an outer ring and an inner ring with the rollers inclined in different directions alternately in the circumferential direction.

Cross roller bearings, which are used in reducers for industrial robots, are required to have stable characteristics such as high positioning accuracy, repeatability accuracy, and high moment rigidity.

For example, the cross roller bearing shown in the following Patent Document 1 has an outer ring and an inner ring of an integral structure formed in an annular shape. A V-shaped raceway surface opening inward is formed along the circumferential direction on the inner peripheral surface of the outer ring, and a V-shaped raceway surface opening outward to face the raceway surface of the outer ring is formed along the circumferential direction on the outer peripheral surface of the inner ring. For example, as shown in Figures 9(a) and 9(b), the outer ring 20 has a roller insertion hole 22 for inserting a roller 25 (see Figure 10) from its outer peripheral surface to the outer ring raceway surface 21. Then, from this roller insertion hole 22, a large number of rollers 25 are interposed between the raceway surfaces 21 and 24 of the inner and outer rings 20 and 23 so that the rotation axes of adjacent rollers are alternately perpendicular to each other (see Figure 10). After that, a cover (stop plug) formed in an approximately cylindrical shape that closes the roller insertion hole 22 is provided in the roller insertion hole 22.

Generally, the raceway of a cross roller bearing is not crowned, and is made up of only a straight section inclined at 45 degrees to the axial direction of the bearing. The rolling surfaces of the rollers come into contact with this raceway surface and roll (see paragraph 0012, Figure 1, etc. of Patent Document 1 below).

Patent No. 3739056

When crowning is not applied, as in the cross roller bearing of Patent Document 1, as shown in FIG. 10, the V-shaped outer ring raceway surface 21 and inner ring raceway surface 24 formed on the outer ring 20 and inner ring 23, respectively, and the rolling surfaces of the rollers 25 ideally contact each other over the entire axial direction of the rollers 25.

However, when a moment load is applied, as shown in the distribution of contact surface pressure in Figure 10, edge stress is generated near the groove shoulder side of the V-groove (the edge portion on the inner surface side of the outer ring 20 and the edge portion on the outer surface side of the inner ring 23) and the groove bottom side (the edge portion of the recess 26 formed on the groove bottom of the inner and outer ring raceways 21, 24) (the part marked with the symbol E in Figure 10), and there is a risk of wear, peeling, etc. starting from this part.

In particular, in the type in which a stopper is provided in the roller insertion hole 22 formed in the outer ring 20, the roller 25 comes into contact with the edge portion (the portion circled with a dashed line in FIG. 9(b)) of the recess 26 that extends circumferentially so as to straddle the roller insertion hole 22, and this edge portion is likely to cause peeling on the outer ring raceway surface 21 or chipping of the roller 25. It is possible to apply crowning to the roller 25 to make the distribution of contact surface pressure uniform, but this would require management of the installation direction of the roller 25, which could lead to increased manufacturing costs. In addition, variations in the machining accuracy of the crowning dimensions formed on each roller are likely to reduce the stable operation of the bearing.

Therefore, the objective of this invention is to extend the life of the bearing by making the distribution of contact pressure acting on the raceway surface uniform when a moment load is applied.

In order to solve the above problems, the present invention provides:
an outer ring having a V-groove-shaped outer ring raceway surface formed on an inner diameter side;
an inner ring having a V-groove-shaped inner ring raceway surface formed on an outer diameter side thereof and facing the outer ring raceway surface;
a plurality of rollers disposed over an entire circumference in a circumferential direction between the outer ring raceway surface and the inner ring raceway surface such that the inclination angles of the rollers alternate;
having
A cross roller bearing is configured in which a straight portion having a linear circumferential cross section, a first crowning portion having a predetermined drop amount, and a second crowning portion having a predetermined radius of curvature that smoothly connects the straight portion and the first crowning portion are formed on at least one of the outer ring raceway surface or the inner ring raceway surface.

This reduces edge stress caused by strong localized contact between the raceway surface and the rollers. This makes it possible to more evenly distribute the contact pressure acting on the raceway surface when a moment load is applied, thereby extending the life of the bearing.

In the above configuration, the first crowning portion having a different shape from each other can be formed on the outer ring raceway surface and the inner ring raceway surface.

In this way, the distribution of contact pressure generated on the outer and inner rings can be made uniform, and edge stress can be appropriately reduced.

In each of the above configurations, the first crowning portion may be formed on at least one of the groove bottom side and groove shoulder side of each raceway surface.

In this way, even if edge stress occurs on either the groove bottom side or the groove shoulder side in response to the load conditions, the edge stress can be appropriately reduced.

In the above configuration, the first crowning portion may be formed on the groove bottom side and the groove shoulder side, each having a different shape.

In this way, appropriate drop amounts are set at the groove bottom and groove shoulder sides in response to the distribution of contact pressure when moment load is applied, making it possible to uniformly distribute the contact pressure acting on the raceway surface.

In each of the above configurations, it is preferable that the radius of curvature is within the range of 0.1 mm or more and 3.0 mm or less.

This makes it possible to equalize the contact pressure between the raceway and the rollers, extending the bearing life while ensuring high moment rigidity.

In each of the above configurations, it is preferable that the distance from the intersection of an extension line of the straight portion toward the first crowning portion and an extension line of a straight line connecting both ends of the first crowning portion toward the straight portion in the circumferential cross section to the second crowning portion is within a range of 0.1 μm to 3.0 μm.

This makes it possible to equalize the contact pressure between the raceway and the rollers, extending the bearing life while ensuring high moment rigidity.

In each of the above configurations, the outer ring and the inner ring have an integral structure that is not divided in the axial direction, the outer ring has a roller insertion hole for inserting the roller from its outer circumferential surface to the outer ring raceway surface, and the roller insertion hole is provided with a stopper that closes the roller insertion hole and forms part of the outer ring raceway surface.

This prevents the roller from coming into contact with the edge of the recess that extends circumferentially across the roller insertion hole, which can cause peeling on the outer ring raceway surface or chipping in the roller.

In each of the above configurations, a full roller type configuration can be used in which no cage or spacer is provided to maintain a predetermined distance between adjacent rollers in the circumferential direction.

In this way, more rollers can be placed between the inner and outer rings compared to when a cage or other device is used, improving the rigidity of the cross roller bearing and further extending its lifespan.

In each of the above configurations, the first crowning portion can be formed only on each of the raceway surfaces, and the rollers can be configured without being crowned.

This prevents the stable operation of the bearing from being reduced due to variations in the machining precision of the crowning dimensions formed on each roller, and also reduces manufacturing costs by eliminating the need to manage the installation direction of the rollers.

In each of the above configurations, the first crowning portion may be configured so that the circumferential cross section is composed only of a linear portion.

This makes machining easier than when the circumferential cross section of the first crowning portion is curved, and reduces manufacturing costs.

In this invention, the cross roller bearing is formed with a second crowning portion having a predetermined radius of curvature that smoothly connects the straight portion and the first crowning portion, which makes it possible to uniformly distribute the contact pressure acting on the raceway surface when a moment load is applied, thereby extending the life of the bearing.

FIG. 2 is a partially cutaway front view of a cross roller bearing according to the present invention; Cross-sectional view taken along line II-II in FIG. 1 (first example) 3 is a cross-sectional view of the main part of FIG. 4 is a cross-sectional view of a further essential part of FIG. Cross-sectional view showing the process of attaching a stopper to the outer ring A cross-sectional view showing an example of the distribution of contact pressure acting on a raceway surface. Cross-section of the main part of a cross roller bearing (second example) Cross-section of the main part of a cross roller bearing (third example) (a) is a cross-sectional view of a conventional outer ring, and (b) is a main part of (a). FIG. 1 is a cross-sectional view showing an example of the distribution of contact pressure acting on the raceway surface of 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, the direction parallel to the rotation axis of the cross roller bearing 1 is called the axial direction, the direction perpendicular to the rotation axis is called the radial direction, and the direction along an arc centered on the rotation axis is called the circumferential direction. As shown in Figures 1 and 2, the main components of this cross roller bearing 1 are an outer ring 2, an inner ring 3 arranged coaxially with the outer ring 2 on the inner diameter side of the outer ring 2, and a number of rollers 4 interposed between the outer ring 2 and the inner ring 3. All of these components are made of steel.

The outer ring 2 has an outer raceway surface 5 with a V-groove that is substantially perpendicular to the inner ring 2, and the inner ring 3 has an inner raceway surface 6 with a V-groove that is substantially perpendicular to the outer raceway surface 5 and faces the outer raceway surface 5. In the following description, the deeper side of each raceway surface 5, 6 from the groove shoulder to the groove bottom is referred to as the groove bottom side, and the shallower side is referred to as the groove shoulder side. The groove bottom of each raceway surface 5, 6 has a continuous recess 7 formed around the entire circumference. In addition, the outer ring 2 has a roller insertion hole 8 (see FIG. 5) for inserting the roller 4, which extends from its outer circumferential surface to the outer raceway surface 5, as shown in FIG. 9(a) and (b).

As shown in Figures 2 and 3, straight sections 9, 10 inclined at 45 degrees to the axial direction are formed at the radial midpoint of the inner and outer ring raceways 5, 6. First crowning sections 11 having a predetermined drop amount (the size of the gap between the rolling surface of the roller 4 and the inner and outer ring raceways 5, 6) are formed on the groove bottom and groove shoulder sides of these straight sections 9, 10. The circumferential cross section of the first crowning section 11 is composed only of straight sections, and the drop amount increases toward the groove bottom side, the inner peripheral surface side of the outer ring 2, or the outer peripheral surface side of the inner ring 3.

Between the straight portions 9, 10 and the first crowning portion 11 formed on the groove bottom side and groove shoulder side, a second crowning portion 12 having a predetermined radius of curvature R is formed to smoothly connect the straight portions 9, 10 and the first crowning portion 11. Here, "smoothly" means that the inclination of the surface normal of the second crowning portion 12 changes continuously from the connection with the straight portions 9, 10 to the connection with the first crowning portion 11, and there are no sharp parts or discontinuous parts such as pin angles along the way. The processing of this second crowning portion 12 can be performed by any method that can be mechanically controlled, such as polishing, tumbling, barreling, shot blasting, and superfinishing, or by manual work such as hand lapping.

In FIG. 2 (as well as FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, and FIG. 8, which show cross-sectional views of the main parts of the cross roller bearing 1), the inclination angle of the first crowning portion 11 is exaggerated to make the first crowning portion 11 and the second crowning portion 12 formed on the inner and outer ring raceway surfaces 5 and 6 easier to see visually. However, the actual inclination angle (e.g., about 2 degrees) is sufficiently small, and the radius of curvature R (e.g., about 0.6 mm) is sufficiently large and the angle change from the straight portions 9 and 10 to the first crowning portion 11 is very gradual, so that when a moment load is applied, the inner and outer ring raceway surfaces 5 and 6 and the rolling surfaces of the rollers 4 can come into contact over the entire axial direction of the rollers 4.

The bearing life and moment rigidity based on the shape of the inner and outer ring raceway surfaces 5, 6 composed of the straight portions 9, 10, the first crowning portion 11, and the second crowning portion 12 are strongly related to (1) the radius of curvature R of the second crowning portion 12 shown in FIG. 4, and (2) the distance L between the intersection of the extension line of the straight portions 9, 10 toward the first crowning portion 11 and the extension line of the straight line connecting both ends of the first crowning portion 11 toward the straight portions 9, 10 in the circumferential cross section and the second crowning portion 12. In this first example, the shapes of the first crowning portion 11 and the second crowning portion 12 formed on 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, respectively, are the same. The width of the first crowning portion 11 and the second crowning portion 12 along the depth direction of the V-groove on the inner and outer ring raceway surfaces 5 and 6 can be determined as appropriate, but from the standpoint of pressure management, it is preferable that the total width of both crowning portions 11 and 12 be 50% or less of the width of the straight portions 9 and 10.

The rollers 4 are arranged around the entire circumference between the outer ring raceway surface 5 and the inner ring raceway surface 6 such that the inclination angles of adjacent rollers 4 in the circumferential direction alternate by 90 degrees. The diameter of the rollers 4 is slightly longer than their length in the direction of the rotation axis. This allows the rollers 4 to roll smoothly without the end of the roller 4 in the direction of the rotation axis simultaneously coming into contact with one side of the surface that constitutes the V-groove of the inner and outer ring raceway surfaces 5 and 6 on which the rolling surface of the roller 4 rolls and the other side surface that is approximately perpendicular to the one side.

The rolling surface of the roller 4 is a cylindrical surface with a constant outer diameter over the entire axial direction, and is not crowned. Therefore, when the roller 4 is assembled between the inner and outer ring raceway surfaces 5 and 6, there is no need to manage the assembly direction, and the assembly work can be done smoothly. In this embodiment, a full roller type is used that does not have a cage or spacer to maintain a predetermined distance between adjacent rollers 4 in the circumferential direction, but it is also possible to hold the rollers 4 with a cage or place a spacer between adjacent rollers 4, ensuring a predetermined gap between the rollers 4.

Once the rollers 4 have been installed, as shown in FIG. 5, a stopper 13 is provided in the roller insertion hole 8 formed in the outer ring 2 to close the roller insertion hole 8 and form part of the outer ring raceway surface 5, and a pin 14 is inserted to prevent the stopper 13 from coming loose, completing the assembly of the cross roller bearing 1. The stopper 13 is formed with the recess 7, straight portion 9, first crowning portion 11, and second crowning portion 12, each of which has the same shape in circumferential cross section, so as to be continuous in the circumferential direction with the recess 7, straight portion 9, first crowning portion 11, and second crowning portion 12 formed in the outer ring raceway surface 5.

In the first example, crowning is formed on both the groove bottom side and groove shoulder side of the inner and outer ring raceway surfaces 5, 6, but since the magnitude of stress varies depending on the load conditions, it may be possible to form crowning on only one side of the inner and outer ring raceway surfaces 5, 6, or only one side of the groove bottom side or groove shoulder side. It may also be possible to form crownings of different shapes between the outer ring raceway surface 5 and the inner ring raceway surface 6, or between the groove bottom side and groove shoulder side.

Figure 6 shows an example of the distribution of contact pressure acting on the inner and outer ring raceway surfaces 5, 6 when a moment load of a predetermined magnitude is applied to the assembled cross roller bearing 1. By forming the straight portions 9, 10, the first crowning portion 11, and the second crowning portion 12 on the inner and outer ring raceway surfaces 5, 6, it was confirmed that the edge stress near the groove shoulder side (the edge portion on the inner circumferential surface side of the outer ring 2 and the edge portion on the outer circumferential surface side of the inner ring 3) and the groove bottom side (the edge portion of the recess 7 formed at the bottom of the inner and outer ring raceway surfaces 5, 6) of the V groove is significantly reduced compared to the conventional method (see Figure 10).

In addition, by forming the crowning with the first crowning portion 11 and the second crowning portion 12 as described above, even in a cross roller bearing 1 configured with a stopper 13 in the roller insertion hole 8 formed in the outer ring 2 as shown in Figure 5, it is possible to prevent the roller 4 from coming into contact with the edge portion of the recess 7, which would cause peeling on the outer ring raceway surface 5 starting from this edge portion, or chipping in the roller 4.

This reduction in edge stress may also be achieved by using logarithmic crowning for the first crowning portion 11 and smoothly connecting the straight portions 9, 10 of the inner and outer ring raceway surfaces 5, 6 to the first crowning portion 11 with a tangent. However, logarithmic crowning is difficult to process and can be costly, so the above configuration in which the straight portions 9, 10 and the first crowning portion 11 are connected by the second crowning portion 12, which can be processed relatively inexpensively, is advantageous.

As described above, the difference in bearing life when the second crowning portion 12 is formed between the straight portions 9, 10 and the first crowning portion 11 and when it is not formed was examined. The examination results are shown in Table 1. Sample No. 1 shown in Table 1 shows the results when the second crowning portion 12 is not formed (comparative example), and Sample No. 2 shows the results when the second crowning portion 12 is formed (embodiment).

In sample No. 2 (Example), the radius of curvature R (R2) of the second crowning portion 12 was 0.6 mm, and the distance L from the intersection of the extensions of the straight portions 9, 10 and the first crowning portion 11 to the second crowning portion 12 was 0.5 μm. In sample No. 1 (Comparative Example), the second crowning portion 12 was not formed, but there was a slight rounding (radius of curvature R (R1) = 0.05 mm) at the intersection of the straight portions 9, 10 and the first crowning portion 11, and there was a small distance L of less than 0.1 μm between the intersection of the extensions of the straight portions 9, 10 and the first crowning portion 11 and the rounding.

When both samples were subjected to a bearing durability test, it was confirmed that the bearing life ratio of the embodiment in which the second crowning portion 12 was formed was 2.8 compared to the comparative example in which the second crowning portion 12 was not formed, and the life was significantly improved. This is thought to be because the edge stress caused by the contact between the inner and outer ring raceway surfaces 5, 6 and the roller 4 was reduced by forming the second crowning portion 12, as shown in Figure 6.

Next, the bearing life and moment rigidity were evaluated when the radius of curvature R of the second crowning portion 12 was changed. The evaluation results are shown in Table 2. In Table 2 (as in Table 3), the symbol "◎" means particularly excellent, "〇" means excellent, and "×" means poor (possibly causing problems in practical use). The symbol "-" means that the superiority gradually changes from "◎ → 〇 → ×" as the straight portions 9 and 10 become shorter as the radius of curvature R increases. In addition, when the radius of curvature R becomes even larger, the first crowning portion 11 may disappear and the shape may be composed only of the recess 7, the second crowning portion 12, and the straight portions 9 and 10. This also applies when the distance L exceeds 3.0 μm in Table 3 described later.

These evaluation results reveal that a good bearing life and moment rigidity can be achieved when the curvature radius R is within the range of 0.1 mm or more and 3.0 mm or less. In particular, the bearing life was particularly excellent when the curvature radius R was within the range of 0.6 mm or more and 3.0 mm or less. On the other hand, it was revealed that when the curvature radius R is 0.05 mm or less, it is possible that a practical bearing life cannot be ensured, and that when the curvature radius R exceeds 3.0 mm, both the bearing life and moment rigidity decrease.

Furthermore, the bearing life and moment rigidity were evaluated when the distance L between the intersection of the extension lines of the straight portions 9, 10 and the first crowning portion 11 and the second crowning portion 12 was changed. The evaluation results are shown in Table 3.

These evaluation results reveal that good bearing life and moment stiffness can be achieved when distance L is in the range of 0.1 μm or more and 3.0 μm or less. In particular, bearing life was particularly excellent when distance L was in the range of 0.2 μm or more and 3.0 μm or less. On the other hand, it was revealed that when distance L is 0.1 μm or less, it is possible that a practical bearing life cannot be ensured, and that when distance L exceeds 3.0 μm, both bearing life and moment stiffness decrease.

The evaluation results shown in Tables 2 and 3 are based on cross roller bearings 1 (e.g., with an outer diameter of about 50 to 240 mm) used in industrial robot reducers, and if the bearing size deviates from this range, the values of the radius of curvature R and distance L that provide good bearing life and moment rigidity may also change.

Another embodiment (second example) of the cross roller bearing 1 according to the present invention is shown in Figure 7. The cross roller bearing 1 according to the second example has the same basic configuration as the first example, but the crowning shape is different between the groove bottom side and the groove shoulder side of the inner and outer ring raceway surfaces 5, 6. That is, in the second example, the circumferential cross section of the first crowning portion 11 on the groove shoulder side of the inner and outer ring raceway surfaces 5, 6 is composed of a curved portion, and the drop amount increases toward the inner peripheral surface side of the outer ring 2 or the outer peripheral surface side of the inner ring 3.

In this second example, the second crowning portion 12 is formed between the straight portions 9, 10 and the first crowning portion 11, which is composed of a curved portion, and as in the first example, the edge stress can be significantly reduced compared to the conventional method. In the second example, the circumferential cross-sectional shape of the first crowning portion 11 is linear on the groove bottom side and curved on the groove shoulder side, but the shape of the first crowning portion 11 can be changed appropriately in some cases, such as by making it curved on the groove bottom side and linear on the groove shoulder side, or by making it curved on both the groove bottom side and the groove shoulder side. In some cases, the shape can be curved with a curvature that changes along the way. In some cases, the crowning can be formed only on one side of the inner and outer ring raceways 5, 6.

When the first crowning portion 11 is curved, the distance L is defined as the distance between the intersection of an extension line of the straight portions 9 and 10 toward the first crowning portion 11 and an extension line of the straight line connecting both ends of the first crowning portion 11 toward the straight portions 9 and 10, and the point where the bisector of the angle formed by both extension lines intersects with the second crowning portion 12.

Figure 8 shows yet another embodiment (third example) of the cross roller bearing 1 according to the present invention. The cross roller bearing 1 according to the third example also has the same basic configuration as the first example, but the crowning shape is different between the groove bottom side and the groove shoulder side of the inner and outer ring raceway surfaces 5, 6. That is, in the third example, the width of the first crowning portion 11 along the depth direction of the V groove is wider on the groove shoulder side than on the groove bottom side, and the drop amount increases toward the groove bottom side or the inner peripheral surface side of the outer ring 2 or the outer peripheral surface side of the inner ring 3.

In this third example, a second crowning portion 12 is also formed between the straight portions 9, 10 and the first crowning portion 11, and as in the first example, edge stress can be significantly reduced compared to the conventional method. In the third example, the width of the first crowning portion 11 is wider on the groove shoulder side than on the groove bottom side, but it may also be possible to make it wider on the groove bottom side than on the groove shoulder side. Also, it may also be possible to form a crowning on only one side of the inner and outer ring raceway surfaces 5, 6.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1 Cross roller bearing 2 Outer ring 3 Inner ring 4 Roller 5 Outer ring raceway surface 6 Inner ring raceway surface 8 Roller insertion hole 9, 10 Straight portion 11 First crowning portion 12 Second crowning portion 13 Stopper R Radius of curvature L Distance

Claims (10)

An outer ring (2) having a V-groove-shaped outer ring raceway surface (5) formed on the inner diameter side thereof;
an inner ring (3) having a V-groove-shaped inner ring raceway (6) formed on the outer diameter side thereof and facing the outer ring raceway (5);
a plurality of rollers (4) arranged over the entire circumference in the circumferential direction between the outer ring raceway surface (5) and the inner ring raceway surface (6) such that the inclination angles are alternately changed;
having
At least one of the outer ring raceway surface (5) and the inner ring raceway surface (6) is formed with a straight portion (9, 10) having a linear cross section in a circumferential direction, a first crowning portion (11) having a predetermined drop amount, and a second crowning portion (12) having a predetermined radius of curvature (R) that smoothly connects the straight portion (9, 10) and the first crowning portion (11),
A cross roller bearing , wherein the first crowning portion (11) having a shape different from each other is formed on each of the outer ring raceway surface (5) and the inner ring raceway surface (6). 2. A cross roller bearing according to claim 1 , wherein the first crowning portion (11) is formed on at least one of a groove bottom side and a groove shoulder side of each of the raceway surfaces (5, 6). 3. The cross roller bearing according to claim 2 , wherein the first crowning portion (11) has a shape different from that of the groove bottom side and the groove shoulder side. 4. A cross roller bearing according to claim 1 , wherein the radius of curvature (R) is within the range of 0.1 mm to 3.0 mm. 5. A cross roller bearing according to claim 1, wherein in the circumferential cross section, a distance (L) from an intersection of an extension line of the straight portion (9, 10) toward the first crowning portion (11) and an extension line of a straight line connecting both ends of the first crowning portion (11) toward the straight portion ( 9 , 10) to the second crowning portion (12) is within a range of 0.1 μm or more and 3.0 μm or less. 6. A cross roller bearing according to claim 1, wherein the outer ring (2) and the inner ring (3) have an integral structure that is not divided in the axial direction, the outer ring (2) has a roller insertion hole (8) for inserting the roller (4) from its outer peripheral surface to the outer ring raceway surface (5), and the roller insertion hole (8) is provided with a stopper (13) that closes the roller insertion hole (8) and forms part of the outer ring raceway surface ( 5 ). 7. A cross roller bearing according to claim 1, which is of a full complement type and does not include a cage or spacer for maintaining a predetermined distance between adjacent rollers in the circumferential direction. 8. A cross roller bearing according to claim 1, wherein the first crowning portion (11) is formed only on each of the raceway surfaces (5, 6), and the rollers (4) are not subjected to crowning. 9. The cross roller bearing according to claim 1, wherein the first crowning portion (11) is constituted only by a portion having a linear circumferential cross section. An outer ring (2) having a V-groove-shaped outer ring raceway surface (5) formed on the inner diameter side thereof;
an inner ring (3) having a V-groove-shaped inner ring raceway (6) formed on the outer diameter side thereof and facing the outer ring raceway (5);
a plurality of rollers (4) arranged over the entire circumference in the circumferential direction between the outer ring raceway surface (5) and the inner ring raceway surface (6) such that the inclination angles are alternately changed;
having
At least one of the outer ring raceway surface (5) and the inner ring raceway surface (6) is formed with a straight portion (9, 10) having a linear cross section in a circumferential direction, a first crowning portion (11) having a predetermined drop amount, and a second crowning portion (12) having a predetermined radius of curvature (R) that smoothly connects the straight portion (9, 10) and the first crowning portion (11),
The first crowning portion (11) is formed on at least one of the groove bottom side and the groove shoulder side of each of the raceway surfaces (5, 6),
A cross roller bearing, wherein the first crowning portion (11) having a shape different from each other is formed on each of the groove bottom side and the groove shoulder side.

Images