JP7455030B2 - Rolling element structure and roller bearings - Google Patents

Description

The present invention relates to a rolling element structure and a roller bearing.

Conventionally, in grease-lubricated roller bearings, a cylindrical roller bearing has been proposed that increases the internal grease holding space for lubrication of rolling and sliding contact parts and is suitable for extending the life of the bearing (Patent Document 1).

As shown in FIG. 14, the cylindrical roller bearing described in Patent Document 1 includes an inner ring 53 having an inner ring raceway 52 on an outer peripheral surface 51, an outer ring 56 having an outer ring raceway 55 on an inner peripheral surface 54, and an inner ring raceway of the inner ring 53. 52 and an outer ring raceway 55 of an outer ring 56, the cylindrical roller 57 is rotatably provided, and a retainer 58 that holds the cylindrical roller 57 is provided.

In this case, a pair of flanges 60, 60 are provided along the circumferential direction at both axial ends of the inner peripheral surface of the outer ring 56, and the outer ring raceway 5 is provided between the flanges 60, 60. Cylindrical rollers 57 are arranged at a predetermined pitch along the circumferential direction between the flanges 60, 60. Moreover, each cylindrical roller 57 is held at a predetermined pitch along the circumferential direction by being fitted into a pocket of the retainer 58.

Grooves (grease reservoirs) 61, 61 are provided at the corners between the flanges 60, 60 and the outer ring raceway 55 to retain grease over the entire circumference.

By providing the grease reservoirs 61, 61 in this way, it is possible to prevent grease from scattering and flowing out due to centrifugal force under continuous high-speed rotation of the bearing, and a sufficient amount of grease can be retained inside the bearing. Also, when the bearing rotates at low speed, the grease held in the grooves adheres to the ends of the cylindrical rollers 57, and as the cylindrical rollers 57 rotate, an appropriate amount of grease is distributed through the roller end surfaces to the entire bearing, especially to the cage guide. It is possible to replenish the surface.

Japanese Patent Application Publication No. 2002-276676

However, in the method described in Patent Document 1, the base oil is only supplied to the end of the rolling region (raceway surface), and therefore, a line contact with a wide contact region results in poor lubrication. Furthermore, since the grease reservoir does not have a function of promoting base oil separation, there is an insufficient supply of base oil from the grease reservoir to the raceway surface.

Therefore, the present invention provides a rolling element structure and a roller bearing that can promote separation of base oil from grease, supply base oil of grease into rolling surfaces, and prevent oil film from running out.

The rolling element structure of the present invention includes a first member having a first rolling surface, a second member having a second rolling surface, and a first rolling surface of the first member and a second rolling surface of the second member. A rolling element structure that includes a plurality of rolling elements that roll between rolling elements and is lubricated with grease, a first rolling element of the first member and a second rolling element of the second member. and the outer circumferential rolling surface of the rolling element, at least one of the rolling surfaces is provided with a flow path extending from the rolling surface area to the outer edge side of the rolling surface, and a peripheral surface connected to the flow path is provided. A grease reservoir arranged along the direction is provided, the flow path has a periodic structure of grating-like unevenness, and a surface opposite the rolling surface on which the flow path is provided corresponds to the flow path. It has a rolling motion in which a region and a region not corresponding to the flow path are formed, or a rolling motion in which a region not corresponding to the flow path is formed after rolling of a region corresponding to the flow path.

According to the rolling element structure of the present invention, the flow path from the rolling surface region toward the outer edge of the rolling surface is provided with a periodic structure of grating-like unevenness, so the surface area of the flow path is large and wettability is improved. Capillary action promotes base oil mobility. As a result, the lubricating oil (base oil) of the grease removed from the center of the rolling element contact area can be drawn out, and the base oil can also be supplied to the contact area near the axial center of the rolling element where the oil film is expected to run out. That is, the entire surface of the periodic structure can be kept wet with the base oil. In particular, pressure is gradually applied to the periodic structure holding the base oil of the grease from the ends of the periodic structure due to the rolling of the rolling elements. Therefore, the base oil in the periodic structure is pushed out to the unprocessed surface of the periodic structure ahead of the contact part with the rolling element in the rolling direction, and by supplying the base oil to this unprocessed surface, an oil film is created. Cutting can be effectively prevented. Note that since the rolling surface provided with the periodic structure and its counterpart surface form a so-called Hertzian contact, for example, if a flow path is formed on the rolling surface of the first member, the rolling element The base oil in the periodic structure is also pushed out to the rear side in the rolling direction from the contact portion with the base oil, and the base oil is supplied to the unprocessed surface of the periodic structure on the rear side in the rolling direction.

By the way, by providing the flow path, a step is created between the flow path and the rolling surface where the flow path is not provided. However, rolling in which a portion corresponding to the flow path and a portion not corresponding to the flow path are formed, or rolling in which a portion not corresponding to the flow path is formed after rolling of a portion corresponding to the flow path (preferably is a rolling process in which a part that does not correspond to the flow path is formed, and then a part that corresponds to the flow path and a part that does not correspond to the flow path are formed. , this rolling element can roll smoothly without getting caught. In addition, if the surface on the other side of the rolling surface provided with a flow path is a rolling surface in which a part corresponding to the flow path and a part not corresponding to the flow path are formed, the roller and the other side's rolling surface are always Rolling motion can be performed between the moving surface and the moving surface without running out of oil. In addition, even if the roller has a rolling motion in which a part that does not correspond to the flow path is formed after the part corresponding to the flow path rolls, the base oil adhering to the rollers prevents the rolling movement from running out of oil. It can be performed.

Furthermore, in the present invention, by providing a grease reservoir that is communicated with the flow path and arranged along the circumferential direction, the base oil that is about to flow out from the rolling surface can be collected in the grease reservoir, and the base oil can be collected from the grease reservoir. Base oil can be supplied to the rolling surfaces.

By providing a periodic structure of grating-like irregularities in the grease reservoir, wettability is improved by increasing the surface area, and the effect of capillary phenomenon is added, promoting base oil separation and base oil mobility of grease. The base oil separated from the grease spreads within the grease reservoir and is supplied into the rolling region via a flow path communicating with the grease reservoir from within the rolling region, thereby making it possible to maintain low friction over a long period of time.

The flow path may be composed only of a periodic structure of grating-like unevenness, or may be composed of a groove and a periodic structure of grating-like unevenness formed in the groove. In a structure consisting of a groove and a periodic structure of grating-like unevenness formed in the groove, even if the rolling surface with the flow path wears out due to long-term use, the periodic structure remains intact. This results in a rolling element structure that is not lost and has excellent durability.

The flow path and the grease reservoir may be formed in the first member, the second member, or the rolling element.

Preferably, a grease thickener is supported on the periodic structure of grating-like unevenness of the flow path. With this configuration, the retention and mobility of the base oil are improved, and the ability to supply the base oil into the rolling region is improved.

It is preferable that the periodic structure of the grating-like unevenness has a height that changes continuously with the apexes of the protrusions being non-flat surfaces. With this configuration, the opening becomes wider and the base oil can be taken in efficiently.

It is preferable that the periodic structure of the grating-like unevenness has an unevenness of 50 nm or more and 10 μm or less, and a periodic pitch of 10 μm or less. That is, this periodic structure has a height that changes continuously, and the height difference between the unevenness (the height from the bottom of the concave part to the top of the convex part) is 50 nm or more and 10 μm or less, and the periodic pitch is 10 μm or less. be. With this configuration, retention and mobility of the base oil can be improved. When the irregularities of the periodic structure are less than 50 nm, a sufficient amount of the thickener cannot be supported, and when the irregularities and the periodic pitch exceed 10 μm, most of the thickener and base oil may flow out.

It is preferable that the periodic structure of grating-like unevenness of the flow path is provided in a plurality of orientation directions. That is, it is preferable to provide a plurality of periodic structures with different orientation directions. The periodic structure of grating-like irregularities is provided in multiple orientation directions, which improves the compatibility (wetting) between the flow path and the base oil, increases the surface area, improves wettability, and increases the effect of capillary phenomenon to improve flow. The lubricant can be quickly wetted and spread in the direction of progression and width of the road. That is, in a periodic structure that develops in a certain direction, the lubricant first spreads and spreads, and then the lubricant spreads and spreads from the periodic structure to a periodic structure that develops in another direction. As a result, the circulation of the base oil is improved, the supply of the base oil to the raceway is improved, and it is possible to prevent the oil film from running out on the raceway.

A first roller bearing of the present invention includes an inner ring having an inner rolling surface on its outer circumferential surface, an outer ring having an outer rolling surface on its inner circumferential surface, and an outer rolling force between the inner rolling surface of the inner ring and the outer ring. A radial roller bearing comprising a plurality of rollers disposed so as to be freely rollable between surfaces, wherein in the rolling element structure, the first member is the inner ring, and the second member is the outer ring. , the rolling element is the roller.

A second roller bearing of the present invention is a thrust roller bearing comprising a pair of washers and a plurality of rollers disposed between opposing rolling surfaces of the washers, wherein the rolling elements are In the structure, the first member is one washer, the second member is the other washer, and the rolling element is the roller.

According to the present invention, separation of base oil from grease is promoted, the base oil of the grease can be supplied into the rolling surface, and the base oil flowing out from the rolling surface can be efficiently recovered. As a result, it is possible to effectively prevent the oil film from running out on the rolling surfaces, and to provide a rolling element structure that can maintain low friction for a long period of time under grease lubrication.

1 is a sectional view of a main part of a radial roller bearing, which is a rolling element structure of the present invention. FIG. 2 is a simplified perspective view of an inner ring, which is a first member, and rollers, which are rolling elements, of the roller bearing shown in FIG. 1. FIG. FIG. 3 is a plan view of the inner ring in an expanded state. FIG. 3 is a front view of the inner ring in an expanded state. A periodic structure of grating-like unevenness is shown, with (a) being an enlarged plan view and (b) being a cross-sectional profile. FIG. 2 is a simplified diagram of a laser surface processing device used to form a periodic structure. Flow paths are shown, (a) is a cross-sectional view of the flow path having a flat rectangular cross-sectional shape, (b) is a cross-sectional view of the flow path having a flat trapezoidal cross-sectional shape, and (c) is a cross-sectional view of the flow path having a flat trapezoidal cross-sectional shape. FIG. 3 is a cross-sectional view of a flow path having a flat semi-elliptical shape. (a) is a cross-sectional view of the grease reservoir whose cross-sectional shape is a flat rectangular shape, (b) is a cross-sectional view of the grease reservoir whose cross-sectional shape is a flat trapezoidal shape, and (c) is a cross-sectional view of the grease reservoir whose cross-sectional shape is a flat trapezoid. FIG. 3 is a cross-sectional view of a grease reservoir having a flat semi-elliptical shape. Flow paths are shown, in which (a) is a simplified diagram of a first modification, and (b) is a simplified diagram of a second modification. FIG. 7 is a simplified diagram of a third variant of the flow path. FIG. 2 is a simplified perspective view showing a flow path having a periodic structure in a plurality of orientation directions. 1 is a sectional view of a main part of a thrust roller bearing which is a rolling element structure of the present invention. FIG. 13 is a simplified bottom view of one washer shown in FIG. 12; FIG. 2 is a sectional view of a main part of a conventional roller bearing (cylindrical roller bearing).

Embodiments of the present invention will be described below based on FIGS. 1 to 11.

FIG. 1 shows an enlarged view of the main parts of a roller bearing (radial roller bearing) which is a rolling element structure of the present invention. This rolling element structure (roller bearing) has a first rolling surface ( A first member 3 having a second rolling surface (inner rolling surface) 2, a second member 7 having a second rolling surface (outer rolling surface) 6 on an inner circumferential surface 5 consisting of a cylindrical surface, and an inner rolling surface of the first member 3. It includes a plurality of rolling elements 8 that roll between the moving surface 2 and the outer rolling surface 6 of the second member 7, and is lubricated with grease. In this case, the first member 3 constitutes the inner ring 10 of the roller bearing, the second member 7 constitutes the outer ring 11 of the roller bearing, and the rolling elements 8 constitute the rollers 12 of the roller bearing. Grease is a semi-solid or solid product obtained by dispersing a thickener in base oil. The first member 3, rollers 12, and second member 7 may be made of carbon steel, copper, aluminum, platinum, cemented carbide, etc., silicon-based ceramics such as silicon carbide or silicon nitride, or engineered plastics. etc. may be used.

Greases include soap-based greases such as calcium soap grease and lithium soap-based grease, and non-soap-based greases such as urea grease and bentonite grease. Various greases can be used depending on the environment and the like.

Further, rollers 12, which are rolling elements 8, are held in a retainer 13 interposed between an inner ring 10 and an outer ring 11. That is, the cage 13 is provided with pockets 13a at predetermined intervals along the circumferential direction, and a roller 12 is fitted into each pocket 13a so as to be rotatable about its axis.

In this case, as shown in FIGS. 2 to 4, a flow path 20 is provided on the inner rolling surface 2 of the first member 3, which is the inner ring 10, from the rolling surface region toward the outer edge of the rolling surface. A grease reservoir 21 is provided which is communicated with the flow path 20 and arranged along the circumferential direction.

In this case, a pair of grease reservoirs 21, 21 are provided at both ends in the axial direction of the inner ring 10, and flow paths 20 are provided between the pair of grease reservoirs 21, 21 at a predetermined pitch along the circumferential direction. . Each flow path 20 is inclined at a predetermined angle with respect to the grease reservoir 21. The angle of inclination θ is, for example, 0°<θ<90° that satisfies the formula cosθ>W/L, where W is the width of the flow path 20 and L is the dimension between the pair of grease reservoirs 21, 21. be.

As shown in FIG. 7, the flow path 20 is composed of a groove 22 and a periodic structure 25 (see FIG. 5) of grating-like unevenness formed in the groove 22. Various shapes can be adopted as the shape of the groove 22, as shown in FIGS. 7(a, b, c), etc. In FIG. 7(b) shows a groove 22 having a flat trapezoidal cross-sectional shape, and FIG. 7(c) shows a groove 22 having a flattened semi-elliptical cross-sectional shape. The cross-sectional shape of the groove 22 shown in FIG. 1 has a semicircular cross-sectional shape.

The grease reservoirs 21, 21 are also composed of a groove 23 as shown in FIG. 8, and a periodic structure 25 of grating-like unevenness formed in the groove 23 (see FIG. 5). As the shape of the groove 23, various shapes can be adopted as shown in FIGS. 8(a), 8(b), and 8(c). 8(a) shows a groove 23 having a flat rectangular cross-sectional shape, FIG. 8(b) shows a groove 23 having a flat trapezoidal cross-sectional shape, and FIG. 8(c) shows a groove 23 having a flat trapezoidal cross-sectional shape. A groove 23 having a flat semi-elliptical shape is shown.

In this embodiment, when the groove depths of the grease reservoir 21 are da, db, dc, and the groove depths of the flow path 20 are da1, db1, dc1, da, db, dc>da1, db1, dc1, When the width dimensions of the grease reservoir 21 are Wa, Wb, Wc, and the width dimensions of the flow path 20 are Wa1, Wb1, Wc1, Wa, Wb, Wc>Wa1, Wb1, Wc1, but this is not limited to these. do not have.

In other words, even if the groove depth and width of the grease reservoir 21 shown in FIGS. 8(a), 8(b), and 8(c) are different for each shape, the flow path shown in each FIG. 7(a), 7(b), and 7(c) is The depth and width of the grooves 20 may be different for each shape. Further, it is possible to set da, db, dc=da1, db1, dc1, or set Wa, Wb, Wc=Wa1, Wb1, Wc1. Conversely, it is possible to set da, db, dc<da1, db1, dc1, or set Wa, Wb, Wc<Wa1, Wb1, Wc1.

As shown in FIG. 5(a), the periodic structure 25 of grating-like unevenness formed in the flow path 20 and the grease reservoir 21 includes minute recesses 26 and minute protrusions 27 formed alternately at a predetermined pitch. It is what it is.

As shown in FIG. 6, it is formed using a laser surface processing apparatus equipped with a laser generator 31 and an optical system 30. In the laser surface processing apparatus shown in FIG. 6, a laser generator 31 is turned back toward a workpiece W by a mirror 32 and guided to a mechanical shutter 33. During laser irradiation, the mechanical shutter 33 is opened, the laser irradiation intensity can be adjusted by the 1/2 wavelength plate 34 and the polarizing beam splitter 36, the polarization direction is adjusted by the 1/2 wavelength plate 35, and the condenser lens 37 is used to adjust the polarization direction. The surface of the workpiece W on the XYθ stage 39 is irradiated with focused light.

The periodic structure is formed in a self-organized manner by irradiating a linearly polarized laser with an irradiation intensity near the processing threshold and scanning the irradiated portion while overlapping it. In other words, when a linearly polarized laser beam is irradiated onto the workpiece (processing material) W with a fluence near the ablation threshold, the interference between the incident light and the scattered light or plasma wave along the surface of the processing material W results in a radiation of the same magnitude as the laser wavelength. At periodic intervals, there is a slight density difference in the energy distribution. In general processing methods, the entire laser irradiated surface is processed, but by irradiating the laser with an energy density near the processing threshold, high-energy areas can be selectively processed. As a result, a grating-like periodic structure is formed even though laser irradiation is performed with a single optical axis. At this time, as the pulse width of the laser used for processing becomes longer, the periodic structure becomes more disturbed due to scattering of the laser due to thermal effects and interaction with processing evaporates.

The periodic structure 25 of grating-like irregularities has a height that changes continuously, as shown in FIG. 5(b). It is preferable that the difference in height of the unevenness (height from the bottom of the concave portion 26 to the top of the convex portion 27) is 50 nm or more and 10 μm or less, and the periodic pitch is 10 μm or less.

The orientation direction of the periodic structure 25 of the flow path 20 may be a direction along the longitudinal direction of the groove 22, a direction perpendicular to this longitudinal direction, or a direction at a predetermined angle (for example, about 45 degrees). ) may be inclined. Further, the orientation direction of the periodic structure 25 of the periodic structure 25 of the grease reservoir 21 may be parallel to the rolling direction (direction of arrow A in FIGS. 3 and 4), or perpendicular to the rolling direction, or even in a predetermined direction. It may be inclined at an angle (for example, about 45 degrees). Here, the term "parallel direction" refers to being generally parallel, and includes a range that allows for slight inclination due to manufacturing errors. In addition, orthogonal directions refer to substantially orthogonal directions, and include a range that allows for slight inclination due to manufacturing errors.

By the way, as shown in FIG. 2, the rollers 12, which are the rolling elements 8, are disposed with their axial centers perpendicular to the grease reservoir 21, and the flow passages 20 are arranged at a predetermined angle with respect to the grease reservoir 21. It is sloping. Therefore, if the rolling element 8 rolls in the direction of the arrow A with respect to the first member 3, in this embodiment, the rolling element 8 will move to a portion of the inner rolling surface 2 corresponding to the flow path 20. , and a portion of the inner rolling surface 2 that does not correspond to the flow path 20 will always exist.

In the rolling body structure of the present invention, the flow path 20 from the rolling surface region toward the outer edge side of the rolling surface is provided with a periodic structure 25 of grating-like irregularities, so that the surface area of the flow path 20 is large, and the mobility of the base oil is promoted by wettability and capillary action. This allows the lubricating oil (base oil) of the grease that has been removed from the center of the rolling body contact region to be drawn out, and the base oil can be supplied to the contact region near the axial center of the rolling body 8 where oil film breakage is predicted. In other words, the entire surface of the periodic structure 25 can be kept wet with the base oil. In particular, pressure is gradually applied from the end of the periodic structure to the periodic structure 25 that holds the base oil of the grease due to the rolling of the rolling body 8. For this reason, the base oil in the periodic structure 20 is pushed out to the unprocessed surface of the periodic structure ahead of the contact portion with the rolling body 8 in the rolling direction, and the supply of base oil to this unprocessed surface effectively prevents oil film breakage. In addition, the rolling surface on which the periodic structure 25 is provided and its mating surface are in a so-called Hertzian contact state, so for example, if a flow path 20 is formed on the rolling surface 2 of the first member 3, the base oil in the periodic structure 25 is pushed out further rearward in the rolling direction than the contact portion with the rolling body 8, and the base oil is supplied to the unprocessed surface of the periodic structure on this rearward side in the rolling direction.

By the way, by providing the flow path 20, a step is created between the flow path 20 and the rolling surface 2 where the flow path 20 is not provided. However, in the rolling element structure of the embodiment of the present invention, the surface 8a on the other side of the rolling surface 2 provided with the flow path 20 always has a portion corresponding to the flow path 20 and a portion not corresponding to the flow path 20. In a rolling motion where a flow path 20 is formed in the rolling surface 2 of the first member 3, the rolling element 8 is formed relative to the rolling surface 2 of the first member 3. will be rolling. Therefore, the rolling elements 8 can roll smoothly without getting caught on the formed steps. For this reason, the width dimension of the flow path 20, the arrangement pitch of the flow path 20, the inclination angle θ of the flow path 20, etc. are determined so that the surface on the other side of the rolling surface on which the flow path is provided corresponds to the flow path. It is necessary to set it so that it is a rolling motion in which a region and a region that does not correspond to the flow path are formed. With this setting, the rolling elements 8 roll smoothly.

Furthermore, by providing the grease reservoir 21 that is communicated with the flow path 20 and arranged along the circumferential direction, the base oil that is about to flow out from the rolling surface 2 can be collected in the grease reservoir 21, and the grease reservoir 21 Base oil can be supplied to the rolling surface 21 from the base oil.

The flow path 20 is composed of a groove 22 and a periodic structure 25 of grating-like unevenness formed in the groove 22, so that the rolling surface 2 on which the flow path 20 is provided can be used for a long period of time. The periodic structure is not lost even if worn and abraded through use, resulting in a rolling element structure with excellent durability.

Furthermore, the flow path 20 may be configured only by the periodic structure 25 having grating-like irregularities. In this way, even in such a case, even without the groove 22, the surface area of the flow path is large and base oil mobility is promoted by wettability and capillarity, so it is possible to effectively prevent oil film breakage, etc. It is possible to achieve the same effects as in the case where the groove 22 is provided.

It is preferable that the grease reservoir 21 is provided with a periodic structure 25 having grating-like irregularities. With this configuration, wettability is improved by increasing the surface area, and the effect of capillary action is added, and base oil separation and base oil mobility of the grease are promoted. The base oil separated from the grease spreads within the grease reservoir 21 and is supplied into the rolling region through the flow path 20 that communicates with the grease reservoir 21 from within the rolling region to maintain low friction over a long period of time. I can do it.

It is preferable that the periodic structure 25 of the flow path 20 and the grease reservoir 21 has a convex portion 27 apex that is a non-flat surface so that the height thereof changes continuously. With this configuration, the opening becomes wider and the base oil can be taken in efficiently.

It is preferable that the irregularities of the periodic structure 25 of the flow path 20 and the grease reservoir 21 are 50 nm or more and 10 μm or less, and the periodic pitch is 10 μm or less. In other words, the periodic structure 25 has a height that continuously changes, and has a height difference between concave and convex portions (height from the bottom of the concave portion to the top of the convex portion) of 50 nm or more and 10 μm or less, and a periodic pitch of 10 μm or less. It is. With this configuration, retention and mobility of the base oil can be improved. If the irregularities of the periodic structure 25 are less than 50 nm, a sufficient amount of the thickener cannot be supported, and if the irregularities and the periodic pitch exceed 10 μm, most of the thickener and base oil may flow out.

However, if the interval between the flow paths 20 is set relatively large, the roller 12 will have a portion corresponding to the flow path 20 and a portion not corresponding to the flow path 20. After rolling, a portion that does not correspond to the flow path 20 will be formed. Has rolling motion. This may be the case.

By the way, when the surface opposite to the rolling surface provided with the flow path 20 is a rolling surface in which a portion corresponding to the flow path 20 and a portion not corresponding to the flow path 20 are formed, the rollers 12 and It is possible to perform rolling motion with the mating rolling surface without running out of oil. On the other hand, even if the rolling motion is such that a portion not corresponding to the flow path 20 is formed after the portion corresponding to the flow path 20 rolls, the base oil adhering to the rollers 12 prevents the oil from running out. Rolling motion can be carried out without any occurrence. Note that if the rolling motion in which a portion that does not correspond to the flow path 20 is formed becomes long, there is a risk that oil will run out. Therefore, in order to prevent oil from running out, the distance between adjacent channels 20 can be varied depending on the width W of the channels 20, the inclination angle θ of the channels 20, the roller diameter, the grease used, etc. Must be set. Moreover, by having a rolling motion in which a region corresponding to the flow path 20 and a region not corresponding to the flow path 20 are formed after the rolling in which a region that does not correspond to the flow path 20 is formed, This rolling element 8 can roll smoothly without getting caught on the step.

Next, FIGS. 9A and 9B show a modification of the flow path 20, which has a bent portion 40 at an intermediate portion of the flow path 20 (an intermediate portion between the grease reservoirs 21 and 21). That is, the flow path 20 shown in FIG. 9(a) includes a first flow path 41A that slopes in the rolling direction (direction of arrow A) from one grease pool 21 (21A), and a first flow path 41A that slopes in the rolling direction (direction of arrow A) from one grease pool 21 (21A). It consists of a second flow path 41B that is inclined in the rolling direction (direction of arrow A).

In addition, the flow path 20 shown in FIG. 9(b) includes a first flow path 41C that slopes from one grease reservoir 21 (21A) in the direction of arrow B, which is opposite to the rolling direction (direction of arrow A), and A second flow path 41D is formed from the reservoir 21 (21B) and slopes in the direction of arrow B, which is opposite to the rolling direction (direction of arrow A).

The flow path 20 shown in FIG. 9 may also be configured with only the periodic structure 25, or may be configured with the groove 22 and the periodic structure 25 provided within the groove 22.

In these cases as well, the width dimension of the flow path 20, the arrangement pitch of the flow path 20, the inclination angle θ of the flow path 20, etc. are determined according to the following criteria: ``A portion corresponding to the flow path 20 and a portion not corresponding to the flow path are formed.'' It is necessary to set it so that after rolling or rolling of a portion corresponding to the flow path 20, a portion not corresponding to the flow path 20 is formed.

Even in such a flow path 20, the orientation direction of the periodic structure 25 provided can be set arbitrarily. Furthermore, the first channels 41A, 41C and the second channels 41B, 41D may be aligned in the same direction or may be aligned in different directions.

FIG. 10 shows another modification of the flow path. The flow path 20 in this case is curved such that the connection portion 20a of the flow path 20 of one grease reservoir 21A and the connection portion 20b of the flow path 20 of the other grease reservoir 21B face each other. The flow path 20 shown in FIG. 10 may also be configured with only the periodic structure 25, or may be configured with the groove 22 and the periodic structure 25 provided in the groove 22. Further, the orientation direction of the periodic structure 25 can be set arbitrarily.

In this case as well, "rolling in which a region corresponding to the flow path 20 and a region not corresponding to the flow path are formed, or after rolling of a region corresponding to the flow path 20, a region not corresponding to the flow path 20 is formed" It is necessary to set it so that it has a certain amount of rolling motion. In addition, in FIG. 10, the connecting portion 20a of the flow path 20 of one grease reservoir 21A and the connecting portion 20b of the flow path 20 of the other grease reservoir 21B face each other, but it is arranged so that they do not face each other. The flow path 20 may be curved.

Therefore, even if the device has the flow path 20 shown in FIGS. 9(a), (b) and 10, it is possible to achieve the same effects as the device having the flow path 20 shown in FIGS. 1 and 2. .

Next, in the flow path 20 shown in FIG. 11, the periodic structure 25 is provided in a plurality of orientation directions. That is, at the bottom of the groove 22, a first periodic structure 25a whose orientation direction is the longitudinal direction of the groove 22, and second and third periodic structures 25b arranged on both sides of the first periodic structure 25a, 25c. The orientation direction of the second and third periodic structures 25b and 25c is along the width direction of the groove 22, which is orthogonal to the longitudinal direction of the groove 22. Further, even if the periodic structure is provided in a plurality of orientation directions as described above, the cross-sectional shape of the groove 22 can be configured in various shapes as shown in FIG. 7 and the like.

In this way, by providing the periodic structure 25 of grating-like unevenness in a plurality of orientation directions, the compatibility (wetting) between the flow path 20 and the base oil is improved, and the surface area is increased, improving wettability and improving capillary flow. With the added effect of this phenomenon, the lubricant can be quickly wetted and spread in the propagation direction and width direction of the flow path. That is, in the periodic structure 25 that develops in a certain direction, the lubricant first wets and spreads, and then the lubricant spreads and spreads from the periodic structure 25 to the periodic structure 25 that develops in another direction. As a result, the circulation of the base oil is improved, the supply of the base oil to the raceway is improved, and it is possible to prevent the oil film from running out on the raceway.

Further, the orientation direction is not limited to that shown in FIG. 11, and the orientation direction of the first periodic structure 25a is along the width direction of the groove 22, which is orthogonal to the longitudinal direction of the groove 22. The orientation direction of the three-period structure 25a may be along the longitudinal direction of the groove 22. That is, the orientation direction of each periodic structure 25a, 25b, 25c can be set arbitrarily. Further, the periodic structure 25 is not limited to the first, second, and third periodic structures 25a, 25b, and 25, and may have a fourth or more periodic structure. In such a case as well, each orientation direction is set arbitrarily, and it is preferable that the orientation directions of at least two periodic structures 25 are different.

In the embodiment described above, the flow path 20 and the grease reservoir 21 were provided on the inner rolling surface 2 of the first member 3, which is the inner ring 10, but in another embodiment, the outer side of the second member 7, which is the outer ring 11, The flow passage 20 and the grease reservoir 21 may be provided on the rolling surface 6, or the flow passage 20 and the grease reservoir 21 may be provided on the outer peripheral rolling surface 8a of the rolling element 8 as the roller 12.

Even in such other embodiments, the same effects as those in which the flow passage 20 and the grease reservoir 21 are provided on the inner rolling surface 2 of the inner ring 10 can be achieved.

By the way, FIG. 12 shows a thrust roller bearing which is a rolling element structure of the present invention. This thrust roller bearing consists of a pair of flat ring-shaped washers 51 and 52, and a plurality of bearings arranged at a predetermined pitch along the circumferential direction between rolling surfaces 51a and 52a of the washers 51 and 52 facing each other. rollers 53 as rolling elements 8, and a retainer 54 that holds the rollers 53 at a predetermined pitch. That is, one washer 51 is the first member 3 whose inner surface (the surface facing the other washer 52) is the first rolling surface 2 (51a), and the other washer 52 is the first member 3 whose inner surface (opposite surface of the other washer 52) is the first rolling surface 2 (51a). The opposing surface of one washer 51 is the second member 7 which is the second rolling surface 6 (52a), and the rollers 53 are the rolling elements 8.

In this case, as shown in FIG. 13, the rolling surface 51a of one washer 51 is provided with a flow path 20 extending from the rolling surface region toward the outer edge of the rolling surface, and is communicated with the flow path 20. Grease reservoirs 21, 21 are provided along the circumferential direction. That is, the grease reservoir 21 includes an annular outer diameter grease reservoir 21 disposed on the outer diameter side and an annular inner diameter grease reservoir 21 disposed on the inner diameter side. and the inner diameter side grease reservoir 21 are communicated with each other through a plurality of channels 20 arranged at a predetermined pitch along the circumferential direction. Further, the flow path 20 is inclined at a predetermined angle θ1 with respect to the radial direction. The predetermined angle θ1 is, for example, 0 that satisfies the formula cos θ1>W/L, where W is the width of the flow path 20 and L is the distance between the inner diameter side grease reservoir 21 and the outer diameter side grease reservoir 21. °<θ<90°.

Each flow path 20 has a periodic structure 25 of grating-like unevenness, and a surface 52a on the other side of the rolling surface 51a on which this flow path 20 is provided is located between a portion corresponding to the flow path 20 and the flow path. A rolling movement in which a portion that does not correspond to the flow path 20 is formed, or a rolling movement in which a portion that does not correspond to the flow path 20 is formed after a portion that corresponds to the flow path 20 is rolled. Further, a periodic structure 25 is also formed in the grease reservoirs 21, 21.

Therefore, even in such thrust roller bearings, as with radial roller bearings, the separation of the base oil from the grease is promoted, and the base oil of the grease is supplied to the rolling surfaces, and the oil flows out from the rolling surfaces. It is possible to efficiently recover the base oil that is present in the bearing.This effectively prevents the oil film from running out on the rolling surface, and maintains low friction for a long period of time under grease lubrication.

By the way, the flow path 20 of this thrust roller bearing is formed by a groove 22 having a cross-sectional shape as shown in FIGS. , the grease reservoirs 21, 21 are also formed by a groove 23 having a cross-sectional shape as shown in FIGS.

Further, the periodic structure 25 of the thrust roller bearing is preferably formed using a laser surface processing apparatus as shown in FIG. 6, and has irregularities of 50 nm or more and 10 μm or less and a periodic pitch of 10 μm or less. The periodic structure 25 of the flow path 20 may be oriented in a direction along the longitudinal direction of the groove 22, or perpendicular to the longitudinal direction, or at a predetermined angle (for example, It may be inclined at an angle of about 45 degrees. Furthermore, whether the orientation direction of the periodic structure 25 of the periodic structure 25 of the grease reservoir 21 is along the circumferential direction or along the radial direction, a predetermined angle (for example, It may be inclined at an angle of about 45 degrees.

The flow path 20 of the thrust roller bearing may be composed only of the periodic structure 25 of grating-like unevenness. The flow path 20 of the thrust roller bearing may have a bent portion as shown in FIGS. 9(a) and 9(b), or may be curved as shown in FIG. 10. Furthermore, as shown in FIG. 11, the periodic structure 25 may be provided in a plurality of orientation directions.

In the thrust roller bearing, the flow path 20 and the grease reservoir 21 were provided only on the rolling surface 51a of one washer 51, but in another embodiment, the rolling surface 52a of the other washer 52, The passage 20 and the grease reservoir 21 may be provided, or the flow passage 20 and the grease reservoir 21 may be provided in the rolling element 53.

The present invention is not limited to the above embodiments and can be modified in various ways. For example, in the illustrated example, both ends of the roller 12 in the axial direction reach a pair of grease reservoirs 21, 21. It may not reach the pair of grease reservoirs 21, 21, and only one of them may be used as the grease reservoir 21. Further, the cross-sectional shapes of the grooves 22 of the flow path 20 and the grooves 23 of the grease reservoir are not limited to those shown in the above illustrations, and various other shapes such as a V-shape or a half-polygon shape can also be adopted. . Although the grooves 22 of the flow path 20 are semicircular as shown in FIG. 3, the grooves 23 of the grease reservoir 21 may be semicircular.

As the laser used for forming the periodic structure, pulsed lasers such as femtosecond laser, picosecond laser, and nanosecond laser can be used. Further, the roller bearing may be a cylindrical roller bearing, a needle roller bearing, a tapered roller bearing, a self-aligning roller bearing, or the like. The rolling element structure is not limited to roller bearings, but can also be used in other mechanisms, such as constant velocity universal joints that include an inner ring, an outer ring, and rolling elements.

1 Outer circumferential surface 2 Inner rolling surface 3 First member 5 Inner circumferential surface 6 Outer rolling surface 7 Second member 8 Rolling element 10 Inner ring 11 Outer ring 12 Roller 20 Channel 21 Grease reservoir 22 Groove 25, 25a, 25b, 25c periodic structure

Claims (9)

A first member having a first rolling surface, a second member having a second rolling surface, and a rolling surface between the first rolling surface of the first member and the second rolling surface of the second member. A rolling element structure comprising a plurality of moving rolling elements and lubricated with grease,
From the rolling surface area to at least one of the first rolling surface of the first member, the second rolling surface of the second member, and the outer peripheral rolling surface of the rolling element. A flow path toward the outer edge of the rolling surface is provided, and a grease reservoir is provided that is communicated with the flow path and arranged along the circumferential direction, and the flow path and the grease reservoir have a periodic structure of grating-like unevenness. The other side of the rolling surface provided with this flow path is a rolling element in which a part corresponding to the flow path and a part not corresponding to the flow path are formed, or a part corresponding to the flow path. 1. A rolling element structure having a rolling motion in which a portion not corresponding to a flow path is formed after rolling, and the flow path and a grease reservoir are formed in the rolling element . 2. The rolling element structure according to claim 1, wherein the flow path is comprised only of a periodic structure of grating-like unevenness. The rolling element structure according to claim 1, wherein the flow path is composed of a groove and a periodic structure of grating-like unevenness formed in the groove. The rolling element structure according to any one of claims 1 to 3, wherein a grease thickener is supported on the periodic structure of grating-like unevenness of the flow path. The rolling stock according to any one of claims 1 to 4 , wherein the periodic structure of the grating-like unevenness has a convex apex that is a non-flat surface and whose height changes continuously. Dynamic body structure. The rolling element structure according to any one of claims 1 to 5, wherein the periodic structure of the grating-like irregularities has irregularities of 50 nm or more and 10 μm or less and a periodic pitch of 10 μm or less. The rolling element structure according to any one of claims 1 to 6 , wherein the periodic structure of grating-like unevenness of the flow path is provided in a plurality of orientation directions. an inner ring having an inner rolling surface on its outer circumferential surface, an outer ring having an outer rolling surface on its inner circumferential surface, and disposed so as to be freely rollable between the inner rolling surface of the inner ring and the outer rolling surface of the outer ring. A radial roller bearing comprising a plurality of rollers,
The rolling element structure according to any one of claims 1 to 7 , wherein the first member is the inner ring, the second member is the outer ring, and the rolling element is the roller. radial roller bearing. A thrust roller bearing comprising a pair of washers and a plurality of rollers arranged between opposing rolling surfaces of the washers,
In the rolling element structure according to any one of claims 1 to 7 , the first member is one washer, the second member is the other washer , and the rolling element is the roller. Thrust roller bearings are characterized by: