Cross roller bearings and cages for cross roller bearings

Abstract

To provide a cross-roller bearing that ensures smooth rolling of the rollers while improving ease of assembly. [Solution] The cross roller bearing comprises an outer ring, an inner ring, a plurality of rollers, and a cage that holds the plurality of rollers, which is formed by combining a first divided holding portion and a second divided holding portion that are divided in the axial direction. The first divided holding portion includes a first annular portion and a plurality of first protrusions, each provided with a plurality of first roller accommodating grooves for accommodating the first roller. The second divided holding portion includes a second annular portion and a plurality of second protrusions, each provided with a plurality of second roller accommodating grooves for accommodating the second roller. The first divided holding portion is provided with a plurality of first receiving areas formed between the plurality of first protrusions in the circumferential direction to receive the second protrusions. The second divided holding portion is provided with a plurality of second receiving areas formed between the plurality of second protrusions in the circumferential direction to receive the first protrusions.

Description

Technical Field

[0001] The present disclosure relates to a cross roller bearing and a cage for a cross roller bearing.

Background Art

[0002] There has been disclosed a cross roller bearing having an outer ring, an inner ring, a plurality of rollers, and a retainer (see, for example, Patent Document 1). Further, there has been disclosed a rolling bearing having a cage axially divided (see, for example, Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a cross roller bearing, a cage for ensuring smooth rolling of the rollers is required. In such a cross roller bearing provided with such a cage, improvement in assemblability is required from the viewpoint of ensuring good productivity.

[0005] Therefore, one of the objectives is to provide a cross roller bearing and a cage for a cross roller bearing that can improve assemblability while ensuring smooth rolling of the rollers.

Means for Solving the Problems

[0006] A cross-roller bearing according to this disclosure comprises an outer ring having a pair of mutually orthogonal outer ring raceway surfaces on its inner circumferential surface; an inner ring having a common central axis with the outer ring and a pair of mutually orthogonal inner ring raceway surfaces on its outer circumferential surface; a plurality of rollers having rolling surfaces that roll on the outer ring raceway surfaces and the inner ring raceway surfaces, and disposed between the outer ring and the inner ring; and a cage that holds the plurality of rollers, which is formed by combining a first divided holding portion and a second divided holding portion that are divided in the axial direction. The plurality of rollers include a plurality of first rollers whose rolling axes extend in a first direction and a plurality of second rollers whose rolling axes extend in a second direction that is perpendicular to the first direction. The plurality of rollers are arranged alternately in the circumferential direction, with the first rollers and the second rollers being arranged alternately. The first divided holding portion includes a first annular portion and a plurality of first protrusions that are spaced apart in the circumferential direction, extend from the first annular portion toward the second divided holding portion, and each is provided with a plurality of first roller accommodating grooves for accommodating the first rollers. The second divided retaining portion includes a second annular portion and a plurality of second protrusions arranged at intervals in the circumferential direction, extending from the second annular portion toward the first divided retaining portion, and each of which is provided with a plurality of second roller accommodating grooves for accommodating the second roller. The first divided retaining portion is provided with a plurality of first receiving areas formed between the plurality of first protrusions in the circumferential direction to receive the second protrusions. The second divided retaining portion is provided with a plurality of second receiving areas formed between the plurality of second protrusions in the circumferential direction to receive the first protrusions. [Effects of the Invention]

[0007] The above-described cross-roller bearing allows for improved ease of assembly while ensuring smooth rolling of the rollers. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view showing a cross roller bearing including a cage for a cross roller bearing in Embodiment 1 of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view taken when the cross-roller bearing shown in Figure 1 is cut at a cross section including the first roller, which will be described later. [Figure 3]Figure 3 is a schematic cross-sectional view taken when the structure is cut in a cross-section that includes the second roller, which is located next to the first roller shown in Figure 2, in the circumferential direction. [Figure 4] Figure 4 is a schematic perspective view of the first divided holding section. [Figure 5] Figure 5 is a schematic perspective view of a retainer constructed by combining the first divided retaining section and the second divided retaining section. [Figure 6] Figure 6 is a schematic perspective view showing the first and second rollers held in the holder shown in Figure 5. [Figure 7] Figure 7 is an enlarged view showing a portion of the retainer shown in Figure 6, viewed from the outer diameter side. [Figure 8] Figure 8 is an exploded perspective view of the cross roller bearing before the first and second split retaining sections are assembled. [Figure 9] Figure 9 is a schematic cross-sectional view showing a portion of the cage provided in the cross roller bearing in Embodiment 2 of this disclosure. [Figure 10] Figure 10 is a schematic perspective view showing the first segmented retaining section included in the cage provided in the cross roller bearing shown in Figure 9. [Figure 11] Figure 11 is a schematic perspective view of a retainer constructed by combining the first divided retaining section and the second divided retaining section. [Figure 12] Figure 12 is a schematic perspective view showing the first and second rollers held in the retainer shown in Figure 11. [Figure 13] Figure 13 is an enlarged view showing a portion of the retainer shown in Figure 12, viewed from the outer diameter side. [Modes for carrying out the invention]

[0009] [Summary of the Embodiment] The cross roller bearing of this disclosure comprises an outer ring having a pair of mutually orthogonal outer ring raceway surfaces on its inner circumferential surface; an inner ring having a common central axis with the outer ring and a pair of mutually orthogonal inner ring raceway surfaces on its outer circumferential surface; a plurality of rollers having rolling surfaces that roll on the outer ring raceway surfaces and the inner ring raceway surfaces, and disposed between the outer ring and the inner ring; and a cage that holds the plurality of rollers, which is formed by combining a first divided holding portion and a second divided holding portion that are divided in the axial direction. The plurality of rollers include a plurality of first rollers whose rolling axes extend in a first direction and a plurality of second rollers whose rolling axes extend in a second direction that is perpendicular to the first direction. The plurality of rollers are arranged alternately in the circumferential direction, with the first rollers and the second rollers being arranged alternately. The first divided holding portion includes a first annular portion and a plurality of first protrusions that are spaced apart in the circumferential direction, extend from the first annular portion toward the second divided holding portion, and each is provided with a plurality of first roller housing grooves for housing the first rollers. The second divided retaining portion includes a second annular portion and a plurality of second protrusions arranged at intervals in the circumferential direction, extending from the second annular portion toward the first divided retaining portion, and each of which is provided with a plurality of second roller accommodating grooves for accommodating the second roller. The first divided retaining portion is provided with a plurality of first receiving areas formed between the plurality of first protrusions in the circumferential direction to receive the second protrusions. The second divided retaining portion is provided with a plurality of second receiving areas formed between the plurality of second protrusions in the circumferential direction to receive the first protrusions.

[0010] The cross-roller bearing of this disclosure includes a plurality of first rollers and a plurality of second rollers whose rolling axes are orthogonal, thereby enabling it to appropriately withstand radial and thrust loads while suppressing an increase in overall size. Here, the first and second rollers are held by a cage, thus enabling stable holding of the first and second rollers. The cage is divided in the axial direction into a first divided holding section and a second divided holding section, so after arranging a plurality of first and second rollers with rolling axes orthogonal between the outer ring and the inner ring, they can be inserted from both sides in the axial direction. Therefore, assembly can be improved. In this case, the first divided holding section includes a plurality of first protrusions, each provided with a plurality of first roller receiving grooves for accommodating the first rollers, and the second divided holding section includes a second protrusion, each provided with a plurality of second roller receiving grooves for accommodating the second rollers. The first divided holding section is provided with the first receiving area, and the second divided holding section is provided with the second receiving area. As a result, when the first divided holding section and the second divided holding section are combined to form the retainer, each first protrusion is fitted into each second receiving area, and with each second protrusion fitted into each first receiving area, the first roller can be housed in the first roller housing groove and the second roller can be housed in the second roller housing groove. Therefore, while suppressing an increase in the axial dimension and restricting the circumferential movement of the first divided holding section relative to the second divided holding section, multiple first rollers can be appropriately held in multiple first roller housing grooves, and multiple second rollers can be appropriately held in multiple second roller housing grooves. Therefore, the first roller and the second roller can be guided stably when they roll. Based on the above, the cross roller bearing of this disclosure can improve ease of assembly while ensuring the smooth rolling of the rollers.

[0011] In the cross roller bearing described above, the first annular portion may be provided with second roller positioning portions that are formed in a plurality of first receiving regions and are recessed in the axial direction along the outer shape of the second roller. The second annular portion may be provided with first roller positioning portions that are formed in a plurality of second receiving regions and are recessed in the axial direction along the outer shape of the first roller. By doing so, the second roller can be appropriately guided by the second roller positioning portion provided in the first annular portion, and the position of the second roller in the circumferential direction can be stabilized. Also, the first roller can be appropriately guided by the first roller positioning portion provided in the second annular portion, and the position of the first roller in the circumferential direction can be stabilized. Therefore, the first roller and the second roller can roll stably, and smooth rolling of the first roller and the second roller can be further ensured.

[0012] In the cross roller bearing described above, the first roller positioning portion may contact only the rolling surface of the first roller. The second roller positioning portion may contact only the rolling surface of the second roller. By doing so, while suppressing an increase in sliding resistance associated with an increase in the contact area between the cage and each of the first roller and the second roller, the position of the first roller and the position of the second roller can be stabilized. Therefore, it becomes easy to achieve both positioning of the first roller and the second roller and suppression of an increase in sliding resistance.

[0013] In the cross roller bearing described above, the first roller positioning portion may contact the rolling surface of the first roller and a part of the end face of the first roller. The second roller positioning portion may contact the rolling surface of the second roller and a part of the end face of the second roller. By doing so, more reliable positioning of the first roller and more reliable positioning of the second roller can be performed. Therefore, more stable rolling of the first roller and the second roller can be ensured.

[0014] In the cross roller bearing described above, a first engaging portion may be provided on a circumferential side portion of the first protruding portion. A second engaging portion may be provided on a circumferential side portion of the second protruding portion. When the first split holding portion and the second split holding portion are combined, the first engaging portion and the second engaging portion may engage with each other. According to such a configuration, by engaging the first engaging portion and the second engaging portion, the first split holding portion and the second split holding portion can be more stably combined to form a cage. Therefore, the configuration of the cage can be more reliably stabilized.

[0015] In the cross roller bearing described above, the position where the first engaging portion and the second engaging portion engage may be at the center of the cage in the axial direction. By doing so, in the cage formed by combining the first split holding portion and the second split holding portion, it is possible to suppress the load from being biased to either the first split holding portion or the second split holding portion. Therefore, stable holding of the first roller and the second roller by the cage can be carried out over a long period.

[0016] In the cross roller bearing described above, the shape of the first split holding portion may be the same as the shape of the second split holding portion. By doing so, the first split holding portion and the second split holding portion can be made into common parts, and productivity and assemblability can be improved. Therefore, it becomes easy to reduce costs.

[0017] In the cross roller bearing described above, the pair of outer ring raceway surfaces and the pair of inner ring raceway surfaces may each be formed over the entire circumference. By doing so, joints or steps do not occur on each raceway surface. Then, it is possible to suppress fluctuations in rotational torque and prevent deterioration of runout accuracy. Furthermore, fluctuations in preload can also be prevented. Also, since there are no covers or split parts, assemblability can be improved.

[0018] In the cross-roller bearing described above, in a cross section including the rolling axis of the roller, the center of the rolling surface in the direction of the rolling axis of the roller may be in contact with the outer ring raceway and the inner ring raceway. In a cross-roller bearing employing such a configuration, since the center of the rolling surface in the direction of the rolling axis of the roller is in contact with the outer ring raceway and the inner ring raceway, the roller can receive the load in a balanced manner in the direction of the rolling axis of the roller, and the position of the roller can be stabilized. Therefore, the roller can roll smoothly.

[0019] The cage for a cross roller bearing of this disclosure is included in a cross roller bearing comprising: an outer ring having a pair of mutually orthogonal outer ring raceway surfaces on its inner circumferential surface; an inner ring having a common central axis with the outer ring and a pair of mutually orthogonal inner ring raceway surfaces on its outer circumferential surface; and a plurality of rollers having rolling surfaces that roll on the outer ring raceway surfaces and the inner ring raceway surfaces, and disposed between the outer ring and the inner ring, and holds a plurality of rollers. The cage for the cross roller bearing is constructed by combining a first divided holding section and a second divided holding section that are divided in the axial direction. The plurality of rollers include a plurality of first rollers whose rolling axes extend in a first direction, and a plurality of second rollers whose rolling axes extend in a second direction that is perpendicular to the first direction. The plurality of rollers are arranged alternately in the circumferential direction, with the first rollers and the second rollers being arranged alternately. The first divided retaining portion includes a first annular portion and a plurality of first protrusions arranged at intervals in the circumferential direction, extending from the first annular portion toward the second divided retaining portion, and each of which is provided with a plurality of first roller accommodating grooves for accommodating a first roller. The second divided retaining portion includes a second annular portion and a plurality of second protrusions arranged at intervals in the circumferential direction, extending from the second annular portion toward the first divided retaining portion, and each of which is provided with a plurality of second roller accommodating grooves for accommodating a second roller. The first divided retaining portion is provided with a plurality of first receiving areas formed between the plurality of first protrusions in the circumferential direction to receive the second protrusions. The second divided retaining portion is provided with a plurality of second receiving areas formed between the plurality of second protrusions in the circumferential direction to receive the first protrusions.

[0020] Such a cage for cross-roller bearings allows for improved ease of assembly while ensuring the smooth rolling of the rollers.

[0021] [Specific examples of embodiments] Next, an example of a specific embodiment of the cross roller bearing and the cage for the cross roller bearing of this disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals and their descriptions will not be repeated.

[0022] (Embodiment 1) First, Embodiment 1, which is an embodiment of the present disclosure, will be described. Figure 1 is a schematic perspective view showing a cross roller bearing including a cage for a cross roller bearing in Embodiment 1 of the present disclosure. Figure 2 is a schematic cross-sectional view taken when the cross roller bearing shown in Figure 1 is cut in a cross section including the first roller, which will be described later. Figure 2 is a schematic cross-sectional view taken when the cross roller bearing shown in Figure 1 is cut in the cross section indicated by arrow II-II in Figure 1. Figure 3 is a schematic cross-sectional view taken when the cross roller bearing is cut in a cross section including the second roller, which will be described later and is positioned next to the first roller shown in Figure 2 in the circumferential direction. In the figures shown in Figure 1 and below, the direction indicated by arrow X is the axial direction, and the directions indicated by arrows Y and Z are the radial directions. The directions indicated by arrow Y and arrow Z are orthogonal. In the figures shown in Figure 1 and below, the central axis R of the cross roller bearing is shown by a dashed line. In Figure 2, the rolling axis 17a of the first roller is shown by a dashed line, and the center 19a in the direction of the rolling axis of the first roller is shown by a dashed line. In Figure 3, the rolling axis 18a of the second roller is shown by a dashed line, and the center 20a in the direction of the rolling axis of the second roller is shown by a dashed line.

[0023] Referring to Figures 1, 2, and 3, the cross roller bearing 10a of this disclosure includes an outer ring 11a, an inner ring 12a, a plurality of rollers 13a, and a cage (cage for cross roller bearing) 14a. The outer ring 11a is made of steel and is formed as a single unit. The inner ring 12a is also made of steel and is formed as a single unit. The outer ring 11a and the inner ring 12a are each annular. The outer ring 11a and the inner ring 12a share a common central axis R. The cage 14a also shares a common central axis R with the outer ring 11a and the inner ring 12a. In this embodiment, the cage 14a is made of resin. The plurality of rollers 13a include a plurality of first rollers 15a whose rolling axis 17a extends in a first direction, and second rollers 16a whose rolling axis 18a extends in a second direction perpendicular to the first direction. The first roller 15a and the second roller 16a are arranged alternately in the circumferential direction. The cross roller bearing 10a is a bearing that can appropriately withstand both thrust loads and radial loads.

[0024] The outer ring 11a has a pair of outer ring raceway surfaces 21a and 22a on its inner circumferential surface 23a. That is, the inner circumferential surface 23a of the outer ring 11a is provided with an outer ring raceway surface (first outer ring raceway surface) 21a and an outer ring raceway surface (second outer ring raceway surface) 22a. The outer ring raceway surfaces 21a and 22a are perpendicular to each other. That is, the angle between the outer ring raceway surfaces 21a and 22a is 90 degrees. The first roller 15a rolls on the outer ring raceway surface 21a. The second roller 16a rolls on the outer ring raceway surface 22a. Between the outer ring raceway surfaces 21a and 22a in the axial direction, there is a groove 24a that is connected in an annular shape and recessed on the outer circumference. The outer ring raceway surface 21a serves as a guide surface for the first end face 41a of the second roller 16a, which is positioned adjacent to the first roller 15a rolling on the outer ring raceway surface 21a in the circumferential direction, as described later. The outer ring raceway surface 22a serves as a guide surface for the first end face 41a of the first roller 15a, which is positioned adjacent to the second roller 16a rolling on the outer ring raceway surface 22a in the circumferential direction, as described later.

[0025] The inner ring 12a shares a common central axis R with the outer ring 11a. The inner ring 12a has a pair of inner ring raceway surfaces 31a and 32a on its outer circumferential surface 33a. That is, the outer circumferential surface 33a of the inner ring 12a is provided with an inner ring raceway surface (first inner ring raceway surface) 31a and an inner ring raceway surface (second inner ring raceway surface) 32a. The inner ring raceway surfaces 31a and 32a are perpendicular to each other. That is, the angle between the inner ring raceway surfaces 31a and 32a is 90 degrees. The first roller 15a rolls on the inner ring raceway surface 31a. The second roller 16a rolls on the inner ring raceway surface 32a. Between the inner ring raceway surfaces 31a and 32a in the axial direction, there is a groove 34a that is connected in an annular shape and recessed inward. The inner ring raceway surface 31a serves as a guide surface for the second end face 42a of the second roller 16a, which is positioned adjacent to the first roller 15a rolling on the inner ring raceway surface 31a in the circumferential direction, as described later. The inner ring raceway surface 32a serves as a guide surface for the second end face 42a of the first roller 15a, which is positioned adjacent to the second roller 16a rolling on the inner ring raceway surface 32a in the circumferential direction.

[0026] The pair of outer ring raceway surfaces 21a, 22a and the pair of inner ring raceway surfaces 31a, 32a are each formed over the entire circumference. That is, the pair of outer ring raceway surfaces 21a, 22a and the pair of inner ring raceway surfaces 31a, 32a are each seamlessly connected over the entire circumference. There are no raceway surfaces formed by covers on either the outer ring raceway surfaces 21a, 22a or the inner ring raceway surfaces 31a, 32a. The cross roller bearing 10a of this disclosure does not include a hole for inserting the rollers 13a or a cover for closing the hole. The cross roller bearing 10a of this disclosure is assembled by first moving the inner ring 12a to one side relative to the outer ring 11a so that a part of the outer circumferential surface 33a of the inner ring 12a comes into contact with a part of the inner circumferential surface 23a of the outer ring 11a, and then sequentially inserting the rollers 13a through the radial gap formed between the outer ring 11a and the inner ring 12a so that their rolling axes are perpendicular to each other. This will be described later.

[0027] Each of the multiple first rollers 15a includes a first end face 41a, a second end face 42a, and a rolling surface 43a that rolls on the outer ring raceway surface 21a and the inner ring raceway surface 31a. Each of the multiple first rollers 15a rotates on its own axis about a rolling axis 17a. Each of the second rollers 16a includes a first end face 41a, a second end face 42a, and a rolling surface 43a that rolls on the outer ring raceway surface 22a and the inner ring raceway surface 32a. Each of the multiple second rollers 16a rotates on its own axis about a rolling axis 18a. The first rollers 15a and the second rollers 16a are arranged so that their rolling axes 17a and 18a are orthogonal to each other in the circumferential direction between the outer ring 11a and the inner ring 12a. The length of the first roller 15a in the direction of its rolling axis is configured to be slightly shorter than its diameter. The length of the first roller 15a in the direction of its rolling axis is determined based on the diameter of the first roller 15a, the PCD (Pitch Circle Diameter) of the cross roller bearing 10a, and the operating conditions. The same applies to the second roller 16a.

[0028] In a cross-section of the first roller 15a including its rolling axis 17a (Figure 2), the center 45a of the rolling surface 43a of the first roller 15a in the direction of its rolling axis contacts the outer ring raceway surface 21a and the inner ring raceway surface 31a. Similarly, in a cross-section of the second roller 16a including its rolling axis 18a (Figure 3), the center 45a of the rolling surface 43a of the second roller 16a in the direction of its rolling axis contacts the outer ring raceway surface 22a and the inner ring raceway surface 32a. Furthermore, the effective contact length L1 of the rolling surface 43a of the first roller 15a is 40% to 47% of the length of the first roller 15a in the direction of its rolling axis. Likewise, the effective contact length L1 of the rolling surface 43a of the second roller 16a is 40% to 47% of the length of the second roller 16a in the direction of its rolling axis.

[0029] The retainer 14a holds a plurality of rollers 13a, i.e., a plurality of first rollers 15a and a plurality of second rollers 16a. The diameter of the inner circumferential surface 46a of the retainer 14a is larger than the diameter of the outer circumferential surface 33a of the inner ring 12a. In this embodiment, there is a gap 47a in the radial direction between the inner circumferential surface 46a of the retainer 14a and the outer circumferential surface 33a of the inner ring 12a. Also, the diameter of the outer circumferential surface 48a of the retainer 14a is smaller than the diameter of the inner circumferential surface 23a of the outer ring 11a. In this embodiment, there is a gap 49a in the radial direction between the outer circumferential surface 48a of the retainer 14a and the inner circumferential surface 23a of the outer ring 11a. By doing so, even when the retainer 14a undergoes thermal contraction and thermal expansion due to temperature changes, the radial gaps 47a and 49a are provided, thus reducing the risk of the retainer 14a being strongly pressed against the outer ring 11a and the inner ring 12a. Therefore, the increase in resistance due to contact between the retainer 14a and the outer ring 11a and inner ring 12a can be suppressed, and the rotation of the retainer 14a can be made smoother.

[0030] The retainer 14a includes a first divided retaining section 51a and a second divided retaining section 52a that are divided in the axial direction. In this embodiment, the retainer 14a is constructed by combining the first divided retaining section 51a and the second divided retaining section 52a. The first divided retaining section 51a and the second divided retaining section 52a that constitute the resin retainer 14a are manufactured, for example, by injection molding.

[0031] Figure 4 is a schematic perspective view of the first divided retaining section 51a. Figure 5 is a schematic perspective view of the retainer 14a, which is constructed by combining the first divided retaining section 51a and the second divided retaining section 52a. Figure 6 is a schematic perspective view showing the first roller 15a and the second roller 16a being held in the retainer 14a shown in Figure 5. Figure 7 is an enlarged view showing a part of the retainer 14a shown in Figure 6, enlarged from the outer diameter side. Figure 8 is an exploded perspective view of the cross roller bearing 10a before the first divided retaining section 51a and the second divided retaining section 52a are assembled. Note that in Figure 6, the inner ring 12a is also shown for ease of understanding.

[0032] Referring to Figures 4 to 8, the first divided holding portion 51a includes a first annular portion 53a and a plurality of first protrusions 54a. The first annular portion 53a is a circular annular shape that extends in the circumferential direction. In this embodiment, the first annular portion 53a is located on one side of the first divided holding portion 51a in the axial direction. Specifically, the first annular portion 53a is located at the axial end of the first divided holding portion 51a in the direction opposite to that indicated by arrow X.

[0033] Multiple first protrusions 54a are arranged at intervals in the circumferential direction. Each of the multiple first protrusions 54a extends from the first annular portion 53a toward the second divided holding portion 52a. The first protrusions 54a are provided with first roller accommodating grooves 55a for accommodating the first roller 15a. The first roller accommodating grooves 55a are formed to be recessed in accordance with the outer shape of the first roller 15a, specifically the shape of the rolling surface 43a of the first roller 15a. Since the multiple first protrusions 54a are arranged at intervals in the circumferential direction, the multiple first roller accommodating grooves 55a are also arranged at intervals in the circumferential direction.

[0034] The first dividing and holding portion 51a is provided with a plurality of first receiving regions 56a. Each of the plurality of first receiving regions 56a is formed between the plurality of first protrusions 54a in the circumferential direction. Each of the plurality of first receiving regions 56a receives the respective second protrusions 64a, which will be described later.

[0035] Furthermore, a second roller positioning portion 57a ​​is provided in the first annular portion 53a. In this embodiment, multiple second roller positioning portions 57a are provided at intervals in the circumferential direction. Each second roller positioning portion 57a ​​is formed in each first receiving region 56a. Each second roller positioning portion 57a ​​is provided in the circumferential center of each first receiving region 56a. Each second roller positioning portion 57a ​​is recessed in the axial direction along the outer shape of the second roller 16a. In this embodiment, the second roller positioning portion 57a ​​contacts the rolling surface 43a and a portion of the first end face 41a of the second roller 16a. That is, the second roller positioning portion 57a ​​is recessed in the axial direction so as to contact the rolling surface 43a and a portion of the first end face 41a of the second roller 16a.

[0036] In the first divided holding portion 51a, a first engaging portion 58a is provided on the circumferential side of the first protrusion 54a. The first engaging portion 58a is formed such that it tapers towards the tip of the first protrusion 54a in the axial direction. In this embodiment, the first engaging portion 58a is provided to form a step due to the difference in the circumferential width of the first protrusion 54a. The step is provided to be located in the center of the retainer 14a in the axial direction.

[0037] The shape of the second divided holding portion 52a is the same as the shape of the first divided holding portion 51a. That is, the second divided holding portion 52a includes a second annular portion 63a corresponding to the first annular portion 53a, and a plurality of second protrusions 64a corresponding to a plurality of first protrusions 54a. In this embodiment, the second annular portion 63a is located on the other axial side of the second divided holding portion 52a. Specifically, the second annular portion 63a is located at the axial end of the second divided holding portion 52a in the direction indicated by arrow X.

[0038] Multiple second protrusions 64a are arranged at intervals in the circumferential direction. Each of the multiple second protrusions 64a extends from the second annular portion 63a toward the first divided holding portion 51a. The second protrusions 64a are provided with second roller housing grooves 65a for housing the second roller 16a. The second roller housing grooves 65a are formed to be recessed in accordance with the outer shape of the second roller 16a, specifically the shape of the rolling surface 43a of the second roller 16a. Since the multiple second protrusions 64a are arranged at intervals in the circumferential direction, the multiple second roller housing grooves 65a are also arranged at intervals in the circumferential direction.

[0039] The second divided holding portion 52a is provided with a plurality of second receiving regions 66a. Each of the plurality of second receiving regions 66a is formed between the plurality of second protrusions 64a in the circumferential direction. Each of the plurality of second receiving regions 66a receives each of the first protrusions 54a.

[0040] Furthermore, the second annular portion 63a is provided with a first roller positioning portion 67a (see Figure 8, described later). In this embodiment, multiple first roller positioning portions 67a are provided at intervals in the circumferential direction. Each first roller positioning portion 67a is formed in each second receiving region 66a. Each first roller positioning portion 67a is located in the circumferential center of each second receiving region 66a. Each first roller positioning portion 67a is recessed in the axial direction along the outer shape of the first roller 15a. In this embodiment, the first roller positioning portion 67a contacts a part of the rolling surface 43a and the first end surface 41a of the first roller 15a. That is, the first roller positioning portion 67a is recessed in the axial direction so as to contact a part of the rolling surface 43a and the first end surface 41a of the first roller 15a.

[0041] In the second divided holding portion 52a, a second engaging portion 68a is provided on the circumferential side of the second protrusion 64a. The second engaging portion 68a is formed such that it tapers towards the tip of the second protrusion 64a in the axial direction. In this embodiment, the second engaging portion 68a is provided to form a step due to the difference in the circumferential width of the second protrusion 64a. The step is provided to be located in the center of the retainer 14a in the axial direction.

[0042] Next, an example of how to assemble the cross roller bearing 10a of this disclosure will be briefly described. First, the inner ring 12a is placed on the inner diameter side of the outer ring 11a, and the inner ring 12a is shifted radially relative to the outer ring 11a so that a part of the outer circumferential surface 33a of the inner ring 12a comes into contact with a part of the inner circumferential surface 23a of the outer ring 11a. This creates a large gap on the radially opposite side of the contact area. The first roller 15a and the second roller 16a are inserted sequentially through this gap so that their rolling axes are perpendicular to each other. After inserting all of the first rollers 15a and the second rollers 16a, the inner ring 12a is returned to its original position and the first divided retaining part 51a and the second divided retaining part 52a are assembled.

[0043] Then, the first divided holding part 51a is advanced axially so that the tip of the first protruding part 54a is leading. In this embodiment, the first divided holding part 51a is advanced in the direction indicated by arrow B1. The first divided holding part 51a is then inserted into the radial gap between the inner circumferential surface 23a of the outer ring 11a and the outer circumferential surface 33a of the inner ring 12a. At this time, the circumferential positions of the first roller 15a and the second roller 16a are adjusted so that the first roller 15a is housed in each first roller housing groove 55a. Similarly, the second divided holding part 52a is advanced axially so that the tip of the second protruding part 64a is leading. In this embodiment, the second divided holding part 52a is advanced in the direction indicated by arrow B2. The second divided holding part 52a is then inserted into the radial gap between the inner circumferential surface 23a of the outer ring 11a and the outer circumferential surface 33a of the inner ring 12a. Furthermore, the first protrusion 54a is positioned within the second receiving area 66a, and the second protrusion 64a is positioned within the first receiving area 56a. At this time, that is, when the first divided holding part 51a and the second divided holding part 52a are combined, the first engaging part 58a and the second engaging part 68a engage at the axial center. In this way, the first divided holding part 51a and the second divided holding part 52a are combined to form the cage 14a. In this way, the cross roller bearing 10a is assembled.

[0044] The cross-roller bearing 10a described above includes multiple first rollers 15a and multiple second rollers 16a whose rolling axes 17a and 18a are orthogonal to each other. Therefore, it can appropriately withstand radial and thrust loads while suppressing an increase in overall size. Here, the first rollers 15a and second rollers 16a are held by the cage 14a, enabling stable holding of the first rollers 15a and second rollers 16a. Since the cage 14a is divided in the axial direction into a first divided holding section 51a and a second divided holding section 52a, after arranging multiple first rollers 15a and second rollers 16a with their rolling axes 17a and 18a orthogonal to each other between the outer ring 11a and the inner ring 12a, they can be inserted from both sides in the axial direction. Thus, assembly can be improved. In this case, the first divided holding section 51a includes a plurality of first protrusions 54a, each provided with a plurality of first roller accommodating grooves 55a for accommodating the first roller 15a, and the second divided holding section 52a includes a second protrusion 64a, each provided with a plurality of second roller accommodating grooves 65a for accommodating the second roller 16a. The first divided holding section 51a is provided with the first receiving area 56a, and the second divided holding section 52a is provided with the second receiving area 66a. Thus, when the first divided holding section 51a and the second divided holding section 52a are combined to form the holder 14a, each first protrusion 54a is fitted into each second receiving area 66a, and with each second protrusion 64a fitted into each first receiving area 56a, the first roller 15a can be accommodated in the first roller accommodating groove 55a, and the second roller 16a can be accommodated in the second roller accommodating groove 65a. Therefore, while suppressing an increase in the axial dimension and restricting the circumferential movement of the first divided holding portion 51a relative to the second divided holding portion 52a, multiple first rollers 15a can be appropriately held in multiple first roller housing grooves 55a, and multiple second rollers 16a can be appropriately held in multiple second roller housing grooves 65a. Thus, the first rollers 15a and second rollers 16a can be guided stably when they roll.Based on the above, the cross roller bearing 10a of this disclosure makes it possible to improve ease of assembly while ensuring the smooth rolling of the rollers 13a, i.e., the first roller 15a and the second roller 16a.

[0045] In this embodiment, the first annular portion 53a is provided with a second roller positioning portion 57a ​​formed in a plurality of first receiving regions 56a and recessed in the axial direction along the outer shape of the second roller 16a. The second annular portion 63a is provided with a first roller positioning portion 67a formed in a plurality of second receiving regions 66a and recessed in the axial direction along the outer shape of the first roller 15a. Therefore, the second roller positioning portion 57a ​​provided in the first annular portion 53a can appropriately guide the second roller 16a, thereby stabilizing the position of the second roller 16a in the circumferential direction. In addition, the first roller positioning portion 67a provided in the second annular portion 63a can appropriately guide the first roller 15a, thereby stabilizing the position of the first roller 15a in the circumferential direction. Consequently, each roller 13a, i.e., the first roller 15a and the second roller 16a, can be rolled stably, and smooth rolling of the first roller 15a and the second roller 16a can be further ensured.

[0046] In this embodiment, the first roller positioning portion 67a contacts the rolling surface 43a of the first roller 15a and a portion of the first end face 41a of the first roller 15a. The second roller positioning portion 57a ​​contacts the rolling surface 43a of the second roller 16a and a portion of the first end face 41a of the second roller 16a. Therefore, more reliable positioning of the first roller 15a and the second roller 16a can be achieved. Consequently, more stable rolling of the first roller 15a and the second roller 16a can be ensured.

[0047] In this embodiment, a first engaging portion 58a is provided on the circumferential side of the first protrusion 54a. A second engaging portion 68a is provided on the circumferential side of the second protrusion 64a. When the first divided holding portion 51a and the second divided holding portion 52a are combined, the first engaging portion 58a and the second engaging portion 68a engage. With this configuration, by engaging the first engaging portion 58a and the second engaging portion 68a, the first divided holding portion 51a and the second divided holding portion 52a can be combined to form the retainer 14a more stably. Therefore, the configuration of the retainer 14a can be stabilized more reliably.

[0048] In this embodiment, the engagement point between the first engaging portion 58a and the second engaging portion 68a is the center of the retainer 14a in the axial direction. Therefore, in the retainer 14a, which is constructed by combining the first divided retaining portion 51a and the second divided retaining portion 52a, it is possible to suppress the uneven distribution of load on either the first divided retaining portion 51a or the second divided retaining portion 52a. Consequently, stable holding of the first roller 15a and the second roller 16a by the retainer 14a can be achieved over a long period of time.

[0049] In this embodiment, the shape of the first divided holding part 51a is the same as the shape of the second divided holding part 52a. Therefore, the first divided holding part 51a and the second divided holding part 52a can be made from a common part, improving productivity and ease of assembly. Consequently, cost reduction becomes easier.

[0050] In this embodiment, the pair of outer ring raceway surfaces 21a, 22a and the pair of inner ring raceway surfaces 31a, 32a are each formed over the entire circumference. Therefore, no joints or steps occur on each raceway surface. This suppresses fluctuations in rotational torque and prevents a decrease in runout accuracy. Furthermore, fluctuations in preload can also be prevented. In addition, since there are no covers or separate parts, assembly can be improved.

[0051] In this embodiment, in a cross-section including the rolling axis 17a of the first roller 15a, the center 45a of the rolling surface 43a of the first roller 15a in the direction of the rolling axis contacts the outer ring raceway surface 21a and the inner ring raceway surface 31a. Similarly, in a cross-section including the rolling axis 18a of the second roller 16a, the center 45a of the rolling surface 43a of the second roller 16a in the direction of the rolling axis contacts the outer ring raceway surface 22a and the inner ring raceway surface 32a. In a cross-roller bearing 10a employing this configuration, the center 45a of the rolling surface 43a of the first roller 15a and the second roller 16a in the direction of their rolling axes is in contact with the outer ring raceway surfaces 21a, 22a and the inner ring raceway surfaces 31a, 32a. As a result, the load can be evenly distributed between the first roller 15a and the second roller 16a in the direction of their rolling axes, stabilizing the posture of the first roller 15a and the second roller 16a. Therefore, the first roller 15a and the second roller 16a can roll smoothly.

[0052] Furthermore, the cage 14a of this disclosure is included in a cross roller bearing 10a which comprises an outer ring 11a having a pair of mutually orthogonal outer ring raceway surfaces 21a, 22a on its inner circumferential surface 23a, an inner ring 12a having a common central axis R with the outer ring 11a and a pair of mutually orthogonal inner ring raceway surfaces 31a, 32a on its outer circumferential surface 33a, and a plurality of rollers 13a having a rolling surface 43a that rolls on the outer ring raceway surfaces 21a, 22a and the inner ring raceway surfaces 31a, 32a, and is arranged between the outer ring 11a and the inner ring 12a, and holds the plurality of rollers 13a. The cage 14a is constructed by combining a first divided holding part 51a and a second divided holding part 52a which are divided in the axial direction. The plurality of rollers 13a include a plurality of first rollers 15a whose rolling axis 17a extends in a first direction, and a plurality of second rollers 16a whose rolling axis 18a extends in a second direction perpendicular to the first direction. The plurality of rollers 13a are arranged alternately in the circumferential direction, with the first rollers 15a and the second rollers 16a. The first divided holding portion 51a includes a first annular portion 53a and a plurality of first protrusions 54a which are spaced apart in the circumferential direction, extend from the first annular portion 53a toward the second divided holding portion 52a, and each is provided with a plurality of first roller accommodating grooves 55a for accommodating the first rollers 15a. The second divided holding portion 52a includes a second annular portion 63a and a plurality of second protrusions 64a that are spaced apart in the circumferential direction, extend from the second annular portion 63a toward the first divided holding portion 51a, and each is provided with a plurality of second roller accommodating grooves 65a for accommodating the second roller 16a. The first divided holding portion 51a is provided with a plurality of first receiving areas 56a that are formed between the plurality of first protrusions 54a in the circumferential direction and receive the second protrusions 64a. The second divided holding portion 52a is provided with a plurality of second receiving areas 66a that are formed between the plurality of second protrusions 64a in the circumferential direction and receive the first protrusions 54a.

[0053] Such a retainer 14a makes it possible to improve ease of assembly while ensuring the smooth rolling of the roller 13a.

[0054] In this embodiment, the effective contact length of the rolling surface 43a of the roller 13a may be 30% to 60% of the length of the roller 13a in the direction of the rolling axis. By doing so, the rated load can be increased more reliably. The effective contact length of the rolling surface 43a of the roller 13a can be adjusted, for example, by changing the axial width dimension of the grooves 24a and 34a.

[0055] (Embodiment 2) Next, another embodiment, Embodiment 2, will be described. Figure 9 is a schematic cross-sectional view showing a part of the cage 14b provided in the cross roller bearing 10b in Embodiment 2 of this disclosure. Figure 9 is a schematic cross-sectional view when the cross roller bearing 10b is cut in a cross section including the first roller 15a, and corresponds to Figure 2 in Embodiment 1. Figure 10 is a schematic perspective view showing the first divided retaining portion 51b included in the cage 14b provided in the cross roller bearing 10b shown in Figure 9. Figure 11 is a schematic perspective view of the cage 14b configured by combining the first divided retaining portion 51b and the second divided retaining portion 52b. Figure 12 is a schematic perspective view showing the state in which the first roller 15a and the second roller 16a are held in the cage 14b shown in Figure 11. Figure 13 is an enlarged view showing a part of the cage 14b shown in Figure 12, enlarged from the outer diameter side. The cross roller bearing 10b in Embodiment 2 has basically the same configuration as in Embodiment 1 and produces the same effects. However, the cross roller bearing 10b of Embodiment 2 differs from the cross roller bearing 10a shown in Embodiment 1 in that the configuration of the first divided holding portion 51b and the second divided holding portion 52b are different.

[0056] Referring to Figures 9 to 13, the cross roller bearing 10b in Embodiment 2 includes an outer ring 11a, an inner ring 12a, a plurality of rollers 13a including a plurality of first rollers 15a and a plurality of second rollers 16a, and a cage 14b that holds the plurality of rollers 13a. The configuration of the outer ring 11a, inner ring 12a, first rollers 15a and second rollers 16a is the same as in Embodiment 1.

[0057] The retainer 14b includes a first divided retaining section 51b and a second divided retaining section 52b. The retainer 14b is formed by combining the first divided retaining section 51b and the second divided retaining section 52b. The first divided retaining section 51b includes a first annular section 53b and a plurality of first protrusions 54b provided with a plurality of first roller accommodating grooves 55b. The first divided retaining section 51b is provided with a plurality of first receiving areas 56b. The second divided retaining section 52b includes a second annular section 63b and a plurality of second protrusions 64b provided with a plurality of second roller accommodating grooves 65b. The second divided retaining section 52b is provided with a plurality of second receiving areas 66b. The configurations of the multiple first protrusions 54b, the multiple first receiving regions 56b, the multiple second protrusions 64b, and the multiple second receiving regions 66b are the same as those of the multiple first protrusions 54a, the multiple first receiving regions 56a, the multiple second protrusions 64a, and the multiple second receiving regions 66a in Embodiment 1, respectively, so their descriptions will be omitted.

[0058] The first annular portion 53b is provided with a second roller positioning portion 57b formed in a plurality of first receiving regions 56b and recessed in the axial direction along the outer shape of the second roller 16a. The second roller positioning portion 57b contacts only the rolling surface 43a of the second roller 16a. That is, the second roller positioning portion 57b has a shape in which it is cut straight in an oblique direction (second direction) along the rolling axis 18a of the second roller 16a. The second annular portion 63b is provided with a first roller positioning portion 67b formed in a plurality of second receiving regions 66b and recessed in the axial direction along the outer shape of the first roller 15a. The first roller positioning portion 67b contacts only the rolling surface 43a of the first roller 15a. That is, the first roller positioning portion 67b has a shape in which it is cut straight in an oblique direction (first direction) along the rolling axis 17a of the first roller 15a. In this embodiment as well, the shape of the first divided holding portion 51b is the same as the shape of the second divided holding portion 52b.

[0059] The cross-roller bearing 10b described above allows for the stabilization of the positions of the first roller 15a and the second roller 16a while suppressing the increase in sliding resistance that occurs due to the increased contact area between the cage 14b and the first roller 15a and the second roller 16a. Therefore, it becomes easier to achieve both the positioning of the first roller 15a and the second roller 16a and the suppression of the increase in sliding resistance.

[0060] (Other embodiments) In the above embodiment, the first annular portion is provided with a second roller positioning portion, and the second annular portion is provided with a first roller positioning portion. However, the invention is not limited to this configuration, and a configuration without a second roller positioning portion and a first roller positioning portion is also possible.

[0061] Furthermore, in the above embodiment, the first protrusion is provided with a first engaging portion and the second protrusion is provided with a second engaging portion. However, the embodiment is not limited to this, and a configuration without the first and second engaging portions is also possible.

[0062] In the above embodiment, the outer ring and inner ring are considered to be integral parts, but the design is not limited to this, and at least one of the outer ring and inner ring may be constructed by combining multiple components. Furthermore, the outer ring or inner ring may be provided with a hole for inserting a roller, and a cover to seal the hole may be provided.

[0063] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. The scope of the present invention is defined by the claims and is intended to include all modifications in the sense and scope equivalent to the claims. [Explanation of Symbols]

[0064] 10a,10b Cross roller bearing, 11a Outer ring, 12a Inner ring, 13a Roller, 14a,14b Cage, 15a First roller, 16a Second roller, 17a,18a Rolling axis, 19a,20a,45a Center, 21a Outer ring raceway surface (First outer ring raceway surface), 22a Outer ring raceway surface (Second outer ring raceway surface), 23a,46a Inner circumferential surface, 24a,34a Groove, 31a Inner ring raceway surface (First inner ring raceway surface), 32a Inner ring raceway surface (Second inner ring raceway surface), 33a,48a Outer circumferential surface, 41a First end face, 42a Second end face, 43a Rolling surface, 47a,49a Gap, 51a,51b First divided retaining section, 52a,52b Second divided holding portion, 53a, 53b First annular portion, 54a, 54b First protruding portion, 55a, 55b First roller housing groove, 56a, 56b First receiving area, 57a, 57b Second roller positioning portion, 58a First engaging portion, 63a, 63b Second annular portion, 64a, 64b Second protruding portion, 65a, 65b Second roller housing groove, 66a, 66b Second receiving area, 67a, 67b First roller positioning portion, 68a Second engaging portion.

Claims

1. An outer ring having a pair of mutually orthogonal outer ring raceway surfaces on its inner circumference, The outer ring and the central axis are common, and the inner ring has a pair of mutually orthogonal inner ring raceway surfaces on its outer surface, A plurality of rollers having rolling surfaces that roll on the outer ring raceway surface and the inner ring raceway surface, and positioned between the outer ring and the inner ring, It is constructed by combining a first divided holding section and a second divided holding section that are divided in the axial direction, and comprises a holder that holds the plurality of rollers, The aforementioned multiple rollers Multiple first rollers whose rolling axes extend in a first direction, The system includes a plurality of second rollers whose rolling axes extend in a second direction perpendicular to the first direction, The plurality of rollers are arranged such that the first roller and the second roller are alternately arranged in the circumferential direction. The first divided holding part is, The first ring section and, It includes a plurality of first protrusions, each spaced apart in the circumferential direction, extending from the first annular portion toward the second divided holding portion, and each provided with a plurality of first roller accommodating grooves for accommodating the first roller, The second divided holding part is, The second ring section and It includes a plurality of second protrusions, each spaced apart in the circumferential direction, extending from the second annular portion toward the first divided holding portion, and each provided with a plurality of second roller accommodating grooves for accommodating the second roller, The first divided holding portion is provided with a plurality of first receiving regions formed between the plurality of first protrusions in the circumferential direction, for receiving the second protrusions. A cross roller bearing wherein the second divided holding portion is provided with a plurality of second receiving regions formed between the plurality of second protrusions in the circumferential direction, for receiving the first protrusions.

2. The first annular portion is provided with a second roller positioning portion that is formed in the plurality of first receiving regions and is recessed in the axial direction along the outer shape of the second roller, The cross roller bearing according to claim 1, wherein the second annular portion is provided with a first roller positioning portion formed in the plurality of second receiving regions and recessed in the axial direction along the outer shape of the first roller.

3. The first roller positioning unit contacts only the rolling surface of the first roller. The cross roller bearing according to claim 2, wherein the second roller positioning portion contacts only the rolling surface of the second roller.

4. The first roller positioning portion contacts the rolling surface of the first roller and a portion of the end face of the first roller. The cross roller bearing according to claim 2, wherein the second roller positioning portion contacts a portion of the rolling surface and the end face of the second roller.

5. A first engaging portion is provided on the circumferential side of the first protrusion. A second engaging portion is provided on the circumferential side of the second protrusion. The cross roller bearing according to claim 1 or claim 2, wherein the first divided holding portion and the second divided holding portion engage with each other when the two portions are combined.

6. The cross roller bearing according to claim 5, wherein the position where the first engaging portion and the second engaging portion engage is the center of the retainer in the axial direction.

7. The cross roller bearing according to claim 1 or claim 2, wherein the shape of the first divided holding portion is the same as the shape of the second divided holding portion.

8. The cross roller bearing according to claim 1 or claim 2, wherein the pair of outer ring raceway surfaces and the pair of inner ring raceway surfaces are each formed over the entire circumference.

9. The cross-roller bearing according to claim 1 or claim 2, wherein in a cross section including the rolling axis of the roller, the center of the rolling surface in the direction of the rolling axis of the roller is in contact with the outer ring raceway surface and the inner ring raceway surface.

10. A cage for a cross roller bearing, comprising: an outer ring having a pair of mutually orthogonal outer ring raceway surfaces on its inner circumference; an inner ring sharing a central axis with the outer ring and having a pair of mutually orthogonal inner ring raceway surfaces on its outer circumference; and a plurality of rollers having rolling surfaces that roll on the outer ring raceway surfaces and the inner ring raceway surfaces, and positioned between the outer ring and the inner ring, wherein the cage holds the plurality of rollers, It is constructed by combining a first divided holding part and a second divided holding part that are divided in the axial direction. The aforementioned multiple rollers Multiple first rollers whose rolling axes extend in a first direction, The system includes a plurality of second rollers whose rolling axes extend in a second direction perpendicular to the first direction, The plurality of rollers are arranged such that the first roller and the second roller are alternately arranged in the circumferential direction. The first divided holding part is, The first ring section and, It includes a plurality of first protrusions, each spaced apart in the circumferential direction, extending from the first annular portion toward the second divided holding portion, and each provided with a plurality of first roller accommodating grooves for accommodating the first roller, The second divided holding part is, The second ring section and It includes a plurality of second protrusions, each spaced apart in the circumferential direction, extending from the second annular portion toward the first divided holding portion, and each provided with a plurality of second roller accommodating grooves for accommodating the second roller, The first divided holding portion is provided with a plurality of first receiving regions formed between the plurality of first protrusions in the circumferential direction, for receiving the second protrusions. A cage for a cross roller bearing, wherein the second divided holding portion is provided with a plurality of second receiving regions formed between the plurality of second protrusions in the circumferential direction, for receiving the first protrusions.

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