Radial roller bearing

Abstract

The present invention provides a radial roller bearing that can prevent rollers from falling out and allow for improvements in handleability, load bearing, and lubricity.　This radial roller bearing is characterized by comprising: a plurality of rollers that roll on an inner circumferential surface of a housing and / or an outer circumferential surface of a shaft; and a meltable retainer that holds the plurality of rollers in a pre-use state and is melted in an in-use state to allow the plurality of rollers to roll.

Description

Radial roller bearing

[0001] The present invention relates to a radial roller bearing.

[0002] Generally, radial roller bearings are used in various mechanical devices such as the transmission gear support part and the shaft support part of an automotive transmission. In conventional radial roller bearings, those provided with a cage are known for the purpose of preventing the rollers from being damaged and falling off before the assembly of the bearing or holding the rollers at predetermined intervals in the circumferential direction.

[0003] In the cages for radial roller bearings described in Patent Documents 1 and 2, claws for holding the rollers are provided on the column part and the annular part of the cage, respectively, thereby preventing the rollers from falling off to the outside and inside in the radial direction of the cage.

[0004] Further, Patent Document 3 discloses a cylindrical roller dropout prevention tool for preventing the rollers from dropping inside in the radial direction of the cage during transportation or the like. In the technique disclosed in Patent Document 3, after the rollers are incorporated into a cage not provided with means for preventing the rollers from dropping inside in the radial direction of the cage, the roller dropout prevention tool is arranged inside in the radial direction of a plurality of rollers arranged along the circumferential direction. Thereby, the rollers are supported by the cage on the outside in the radial direction and by the roller dropout prevention tool on the inside in the radial direction, and are prevented from dropping out of the cage.

[0005] Japanese Patent Application Laid-Open No. 2021-139422, Japanese Patent Application Laid-Open No. 2001-099162, Japanese Patent Application Laid-Open No. 2017-160931

[0006] However, cages that have a function to prevent rollers from falling out, such as those described in Patent Documents 1 and 2, may require extra work when assembling the rollers into the cage. On the other hand, prioritizing ease of assembly of rollers into the cage may result in the cage's roller-holding function being sacrificed. In such cages, when the bearing does not have raceways, it was sometimes difficult to completely prevent rollers from falling out when assembling the bearing into a mating part such as a housing or shaft member. Furthermore, when the cage has a column or a function to restrict the radial movement of the rollers, it was sometimes difficult to reduce the distance between adjacent rollers in the circumferential direction, making it difficult to increase the number of rollers and improve the load capacity. Moreover, depending on the shape of the cage's column, the flow of lubricant inside the bearing may be obstructed by the column, resulting in an uneven distribution of lubricant during bearing operation and insufficient lubrication performance.

[0007] Furthermore, the roller fall prevention device described in Patent Document 3 is primarily intended to prevent rollers from falling off during transportation. That is, the roller fall prevention device must be removed before the bearing is assembled into the rotating machine, and there are issues with handling, such as the inability to prevent rollers from falling off when the bearing is assembled into the rotating machine.

[0008] The present invention has been made in view of the above problems, and its purpose is to provide a radial roller bearing that can prevent roller detachment and improve handling, load capacity, and lubricity.

[0009] The above objective of the present invention is achieved by the following configuration: (1) A radial roller bearing comprising: a plurality of rollers that roll on at least one of the inner surface of the housing and the outer surface of the shaft; and a meltable retaining material that holds the plurality of rollers in the state before use and melts in the state during use to enable the rolling of the plurality of rollers.

[0010] According to the present invention, it is possible to provide a radial roller bearing that can prevent roller detachment and improve handling, load capacity, and lubricity.

[0011] Figure 1 is a perspective view of a radial roller bearing according to the first embodiment. Figures 2(a) and (b) are cross-sectional views perpendicular to the circumferential direction of the radial roller bearing according to the first embodiment, where Figure 2(a) shows the radial roller bearing alone according to the first embodiment, and Figure 2(b) shows the radial roller bearing according to the first embodiment incorporated into a rotating machine. Figure 3 is a plan view of the radial roller bearing according to the first embodiment viewed from the radial direction. Figure 4 is a cross-sectional view taken in the direction of the A-A arrow in Figure 3. Figures 5(a) and (b) are cross-sectional views perpendicular to the circumferential direction of a radial roller bearing according to a modified example of the first embodiment, where Figure 5(a) shows the radial roller bearing alone according to the modified example of the first embodiment, and Figure 5(b) shows the radial roller bearing according to the modified example of the first embodiment incorporated into a rotating machine. Figure 6 is a perspective view of a radial roller bearing according to the second embodiment. Figures 7(a) and 7(b) are cross-sectional views perpendicular to the circumferential direction of a radial roller bearing according to the second embodiment, where Figure 7(a) shows the radial roller bearing according to the second embodiment in a standalone state, and Figure 7(b) shows the radial roller bearing according to the second embodiment incorporated into a rotating machine. Figures 8(a) and 8(b) are cross-sectional views perpendicular to the circumferential direction of a radial roller bearing according to a modified example of the second embodiment, where Figure 8(a) shows the radial roller bearing according to the modified example of the second embodiment in a standalone state, and Figure 8(b) shows the radial roller bearing according to the modified example of the second embodiment incorporated into a rotating machine.

[0012] (First Embodiment) Hereinafter, embodiments of the present invention will be described based on the attached drawings. Figure 1 is a perspective view of a radial roller bearing according to the first embodiment. Figures 2(a) and 2(b) are cross-sectional views perpendicular to the circumferential direction of the radial roller bearing according to the first embodiment, where Figure 2(a) shows the radial roller bearing according to the first embodiment in a standalone state, and Figure 2(b) shows the radial roller bearing according to the first embodiment assembled into a rotating machine. Figure 3 is a plan view of the radial roller bearing according to the first embodiment as seen from the radial direction. Figure 4 is a cross-sectional view taken in the direction of the A-A arrow in Figure 3.

[0013] As shown in Figures 1, 2(a) and (b), the radial roller bearing 10 comprises a plurality of rollers 100 arranged along the circumferential direction, and a meltable retaining material 20 that holds the plurality of rollers 100 in the state before use of the radial roller bearing 10. In the state of use of the radial roller bearing, the meltable retaining material 20 melts due to lubricants such as grease and oil supplied to the radial roller bearing 10, frictional heat generated by the rotation of the radial roller bearing 10, and external heating. Note that the meltable retaining material 20 shown in Figures 1 to 4 and Figures 5(a) and (b) to 8(a) and (b) described later represents the state before melting.

[0014] In this embodiment, the radial roller bearing 10 does not have raceways such as an outer ring or inner ring. That is, the multiple rollers 100 roll between the inner circumferential surface of the housing 200 and the outer circumferential surface of the shaft 300. Here, the housing 200 and the shaft 300 are components that constitute any rotating machine, and the inner circumferential surface of the housing 200 and the outer circumferential surface of the shaft 300 are arranged coaxially and can rotate relative to each other via the radial roller bearing 10. Furthermore, after the radial roller bearing 10 is incorporated into the housing 200 and shaft 300 of the rotating machine, the molten retaining material 20 melts due to the supply of lubricant to the radial roller bearing 10 or the rise in temperature, and becomes mixed with the lubricant. As a result, the molten retaining material 20 does not hinder the rolling of the multiple rollers 100, and the radial roller bearing 10 incorporated into the rotating machine rotatably supports the shaft 300 relative to the housing 200. Note that the radial roller bearing 10 may also be applied to a rotating machine in which the housing 200 rotates.

[0015] The structure of the meltable retaining material 20 will be described in detail below. As shown in Figures 1 to 4, the meltable retaining material 20 is formed in an annular shape so as to abut the axial ends of a plurality of rollers 100 arranged in the circumferential direction, and has a pair of coaxially arranged annular ends 21, 21, and a plurality of axially extending portions 23 that connect the pair of annular ends 21, 21 in the axial direction and are formed to fill the circumferential gaps between adjacent rollers 100 in the circumferential direction. The meltable retaining material 20 also has a plurality of radially outer slits 25a arranged radially outward of the meltable retaining material 20 and exposing a part of the rolling surface of the plurality of rollers 100, and a plurality of radially inner slits 25b arranged radially inward of the meltable retaining material 20 and exposing a part of the rolling surface of each roller 100. The radially outer slits 25a and radially inner slits 25b extend along the axial direction between adjacent circumferentially extending portions 23.

[0016] In particular, as shown in Figure 4, the axially extending portion 23 is formed in a cross section perpendicular to the axial direction between the circumscribed and inscribed circles of the multiple rollers 100, and is formed to fill the circumferential gaps between adjacent rollers 100 in the circumferential direction. That is, the outer circumferential surface 27 of the axially extending portion 23 has a circular arc shape in cross section and substantially coincides with the circumscribed circles of the multiple rollers 100. Also, the inner circumferential surface 29 of the axially extending portion 23 has a circular arc shape in cross section and substantially coincides with the inscribed circles of the multiple rollers 100.

[0017] As shown in Figures 1 to 4, the radial outer slit 25a is a circumferential gap formed between a pair of adjacent outer circumferential surfaces 27, 27 when viewed from the radial direction. That is, the rolling surface of the roller 100 exposed from the radial outer slit 25a contacts the inner circumferential surface of the housing 200. The radial inner slit 25b is a circumferential gap formed between a pair of adjacent inner circumferential surfaces 29, 29 when viewed from the radial direction. That is, the rolling surface of the roller 100 exposed from the radial inner slit 25b contacts the outer circumferential surface of the shaft 300. By providing the molten holding material 20 with radial outer slits 25a and radial inner slits 25b, the difference between the size of the radial gap formed between the housing 200 and the shaft 300 and the diameter of the roller 100 can be reduced, and the radial roller bearing 10 incorporated into the rotating machine can stably support the rotating shaft 300 with respect to the housing 200. In the illustrated example, the circumferential width Wa of the radially outer slit 25a and the circumferential width Wb of the radially inner slit 25b are constant regardless of the axial position.

[0018] Furthermore, the radial roller bearing 10 of this embodiment is a so-called full-roller bearing, which does not have a cage. In a full-roller bearing, in order to improve the load capacity, adjacent rollers 100 in the circumferential direction may be configured to be in contact with each other. In such a case, the axially extended portion 23 is not formed near the circumference of the pitch circle P (see Figure 4), where adjacent rollers 100 in the circumferential direction are in contact. That is, as shown in particular in Figure 2(a), a circumferential slit 25c is formed between the axially extended portion 23 radially outward from the pitch circle P and the axially extended portion 23 radially inward, so that the rolling surfaces of adjacent rollers 100 in the circumferential direction face each other.

[0019] On the other hand, in a full-roller bearing, there may be gaps between adjacent rollers 100 in the circumferential direction, and adjacent rollers 100 in the circumferential direction may not come into contact with each other. In such cases, it is not always necessary to form a circumferential slit 25c as shown in Figure 2(a).

[0020] The meltable retaining material 20 according to this embodiment consists of a solid oil-soluble polymer. Examples of solid oil-soluble polymers include PIB, methacrylate, polyalkylstyrene, ethylene / propylene, and ethylene / propylene / 1,4-hexadiene polymer as exemplified in U.S. Patent No. 4,014,794. The solid oil-soluble polymer has sufficient rigidity to hold the multiple rollers 100 arranged circumferentially by the meltable retaining material 20, even when the radial roller bearing 10 does not have raceways. The meltable retaining material 20 melts due to the lubricant supplied after the radial roller bearing 10 is incorporated into the rotating machine and due to the rise in temperature. The molten meltable retaining material 20 is agitated together with the lubricant by the rotation of the radial roller bearing 10, and therefore does not hinder the rotation of the multiple rollers 100 during use. Furthermore, the meltable retaining material 20 mixed with the lubricant does not solidify even when the temperature drops after the radial roller bearing 10 stops operating.

[0021] Furthermore, the meltable retaining material 20 is not limited to oil-soluble polymers; it can be any material that is solid before use of the radial roller bearing 10 and melts due to lubrication or rising temperature.

[0022] The method for forming the molten retaining material 20 involves first arranging a cylindrical outer mold having an inner circumferential surface sized to circumscribe multiple rollers 100, and a cylindrical or columnar inner mold having an outer circumferential surface sized to circumscribe multiple rollers 100, coaxially and overlapping when viewed radially. Then, multiple rollers 100 are arranged circumferentially between the outer mold and the inner mold. Subsequently, the raw material for the molten retaining material 20, which has been heated above its melting point to plasticize it, is poured into the gap formed by the outer mold, the inner mold, and the multiple rollers 100, and then cooled. As a result, the solid molten retaining material 20 holds the rollers 100, and a radial roller bearing 10 is obtained.

[0023] As a result of the above molding process, radial outer slits 25a are formed in the portion where the outer mold and the roller 100 come into contact, radial inner slits 25b are formed in the portion where the inner mold and the roller 100 come into contact, and circumferential slits 25c are formed in the portions where adjacent rollers 100 come into contact in the circumferential direction.

[0024] The operation and effects of this embodiment will now be described. As shown in Figure 2(b), the radial roller bearing 10 is installed between the housing 200 and the shaft 300. Subsequently, when lubricant is supplied to the radial roller bearing 10, or when the temperature of the radial roller bearing 10 rises, the molten retaining material 20 melts. As a result, the multiple rollers 100 roll between the housing 200 and the shaft 300 without being hindered by the molten retaining material 20, and the radial roller bearing 10 rotatably supports the shaft 300 relative to the housing 200.

[0025] In conventional radial roller bearings, the movement of the rollers radially inward and radially outward is restricted by a cage or roller fall prevention device, preventing them from falling out of the cage. According to the configuration of this embodiment, the rollers 100 can be held by the molten retaining material 20. As a result, when transporting the radial roller bearing 10 or when assembling the radial roller bearing 10 into a rotating machine, the rollers 100 are prevented from falling out without the use of a cage or roller fall prevention device, making handling easier. In addition, by not using a cage, the rollers 100 can be arranged without gaps in the circumferential direction, resulting in an improvement in load capacity. In particular, the radial roller bearing 10 according to this embodiment is easy to handle because, even when there are no raceways, i.e., when the rollers 100 are arranged between the inner circumferential surface of the housing 200 of the rotating machine and the outer circumferential surface of the shaft 300, the rollers 100 can be held by the molten retaining material 20 without the use of a cage or the like. Furthermore, assembly of the rollers 100 and the molten retaining material 20 is also easy. Furthermore, during the operation of the radial roller bearing 10, the molten retaining material 20 melts due to the lubricant or the rise in temperature, mixing with the lubricant without retaining its original form. As a result, the flow of the lubricant inside the radial roller bearing 10 is not obstructed, and the lubricant can easily spread throughout, thus improving lubrication.

[0026] Here, a modified version of this embodiment will be described. Figures 5(a) and (b) are cross-sectional views perpendicular to the circumferential direction of a radial roller bearing according to a modified version of the first embodiment. Figure 5(a) shows the radial roller bearing according to the modified version of the first embodiment in a standalone state, and Figure 5(b) shows the radial roller bearing according to the modified version of the first embodiment incorporated into a rotating machine. As shown in Figures 5(a) and (b), the radial roller bearing 10 may further include a cage 50 having a plurality of pockets 55 for accommodating a plurality of rollers 100. The cage 50 according to this modification has a pair of coaxially arranged annular portions 51, 51, a plurality of columnar portions 53 connecting the radially outer portions of the pair of annular portions 51, 51 at predetermined intervals in the circumferential direction, and a plurality of pockets 55 formed by the pair of annular portions 51, 51 and the circumferentially adjacent columnar portions 53, 53. Furthermore, the circumferential gap between the circumferentially adjacent columnar portions 53, 53 constituting the pockets 55 is smaller than the diameter of the rollers 100. This prevents the roller 100, which is housed in the pocket 55, from falling out radially outward from the retainer 50.

[0027] In the state before the meltable retaining material 20 melts, the multiple rollers 100 are covered by the meltable retaining material 20 together with the pair of annular portions 51, 51 and columnar portions 53, except for a portion of the rolling surface exposed from the radial outer slit 25a and the radial inner slit 25b. As a result, the multiple rollers 100 are held by the meltable retaining material 20 and the retainer 50.

[0028] Furthermore, the annular end 21 of the molten retaining material 20 is formed to fill the axial gap between the axial ends of the roller 100 and the annular portion 51 of the retainer 50. The annular end 21 also covers the radially outer end and radially inner end of the annular portion 51 of the retainer 50.

[0029] Columnar portions 53 are positioned in the circumferential gaps between adjacent rollers 100 in the circumferential direction. Therefore, the axially extending portion 23 of the molten-holding material 20 is formed to cover the columnar portions 53 in the circumferential gaps between adjacent rollers 100 in the circumferential direction, and the axially extending portion 23 covering the radially outer side of the columnar portions 53 is formed to be thin-walled. In this modified example, there is a gap between adjacent rollers 100 in the circumferential direction, and the rollers 100 do not come into contact with each other. In such a case, the circumferential slit 25c shown in Figure 2(a) is not formed, and the axially extending portion 23 is formed continuously in the radial direction.

[0030] In this modified example, by combining the molten retaining material 20 with a simple cage 50, the amount of material used for the molten retaining material 20 can be reduced, lowering costs while preventing the rollers 100 from falling out. Furthermore, the strength of the radial roller bearing 10 is improved, making it less susceptible to deformation even when external forces are applied during transportation, etc. In addition, when the radial roller bearing 10 is incorporated into a rotating machine, it becomes easier to restrict the axial movement of the rollers 100.

[0031] (Second Embodiment) The radial roller bearing according to the second embodiment of the present invention will be described below. Some explanations of the structure, which is the same as that of the first embodiment, will be omitted. Figure 6 is a perspective view of the radial roller bearing according to the second embodiment. Figures 7(a) and (b) are cross-sectional views perpendicular to the circumferential direction of the radial roller bearing according to the second embodiment, where Figure 7(a) shows the radial roller bearing according to the second embodiment as a standalone unit, and Figure 7(b) shows the radial roller bearing according to the second embodiment incorporated into a rotating machine. Figures 8(a) and (b) are cross-sectional views perpendicular to the circumferential direction of a modified radial roller bearing according to the second embodiment, where Figure 8(a) shows the radial roller bearing according to the modified second embodiment as a standalone unit, and Figure 8(b) shows the radial roller bearing according to the modified second embodiment incorporated into a rotating machine.

[0032] As shown in Figures 6, 7(a) and (b), the radial roller bearing 10 according to this embodiment includes an outer ring 70 which is a raceway ring having a raceway surface 71 on its inner circumference, a plurality of rollers 100 arranged to roll freely along the raceway surface 71, and a molten retaining material 20 that holds the plurality of rollers 100. When the molten retaining material 20 melts due to the supply of lubricant or an increase in temperature, the plurality of rollers 100 roll between the raceway surface 71 of the outer ring 70 and the outer circumference of the shaft 300 in the rotating machine.

[0033] Similar to the first embodiment, the molten retaining material 20 is formed to extend axially between adjacent axially extending portions 23 in the circumferential direction, and has a plurality of radially outer slits (not shown) that expose a portion of the rolling surfaces of a plurality of rollers 100, and a radially inner slit 25b (see Figure 6). In this embodiment, the rolling surfaces of the rollers 100 exposed from the radially outer slits (not shown) are in contact with the raceway surface 71, and the rolling surfaces of the rollers 100 exposed from the radially inner slits 25b are in contact with the outer circumferential surface of the shaft 300.

[0034] The radial roller bearing 10 shown in Figures 6, 7(a) and (b) employs a shell-shaped outer ring obtained by bending a metal plate. However, as shown in Figures 8(a) and (b), the outer ring 70 may be made of a so-called solid type, which is machined from a metal material.

[0035] In this embodiment, with multiple rollers 100 assembled onto the outer ring 70, the gap formed between the multiple rollers 100 and the outer ring 70 is filled with the raw material of a molten retaining material 20 that has been plasticized by heating to a temperature above its melting point, thereby forming a radial roller bearing 10.

[0036] According to this embodiment, the rollers 100 can be held by the molten retaining material 20 even on the raceway surface of the outer ring 70, preventing the rollers 100 from falling out when the radial roller bearing 10 is assembled into a rotating machine without the need for a cage or roller fall prevention device, thus making it easier to handle. Furthermore, by not using a cage, the rollers 100 can be arranged without gaps in the circumferential direction, resulting in improved load capacity. In addition, as the molten retaining material 20 melts due to lubricant or rising temperature, the lubricant can be more easily distributed throughout the inside of the radial roller bearing 10, improving lubrication.

[0037] It should be noted that the present invention is not limited to those exemplified in the above embodiments, and can be modified as appropriate without departing from the spirit of the invention. For example, the radial roller bearing 10 is not limited to the one shown in the first embodiment, in which there are no raceways such as an outer ring and an inner ring, and the rollers 100 roll between the housing 200 and the shaft 300, or the one shown in the second embodiment, in which there is an outer ring 70 with a raceway surface 71 on its inner circumferential surface, and no inner ring. That is, the radial roller bearing 10 includes one that has an inner ring with a raceway surface on its outer circumferential surface, and no outer ring. Furthermore, it is also possible to have both an outer ring and an inner ring.

[0038] Furthermore, since the molten retaining material 20 is molten during the operation of the rotating machine, its shape only needs to be such that it can hold the rollers 100 when they are assembled into the rotating machine. That is, the outer circumferential surface 27 and inner circumferential surface 29 of the molten retaining material 20 do not need to be arc-shaped in cross-section perpendicular to the axial direction. Also, the molten retaining material 20 covers the entire rolling elements of the multiple rollers 100 and does not need to have radial outer slits 25a or radial inner slits 25b formed therein. In addition, the cage of the radial roller bearing shown in the modified example of the first embodiment may have a pair of annular parts, or it may be a so-called comb-shaped cage having, for example, one annular part, and is not limited to the example shape.

[0039] As described above, the following is disclosed in this specification: (1) A radial roller bearing comprising: a plurality of rollers that roll on at least one of the inner surface of the housing and the outer surface of the shaft; and a meltable retaining material that holds the plurality of rollers in a state before use and melts in a state during use to enable the rolling of the plurality of rollers. This configuration makes it possible to provide a radial roller bearing that can prevent rollers from falling out and improve handling, load capacity, and lubricity.

[0040] (2) The radial roller bearing according to (1), characterized in that the meltable retaining material can be melted by a lubricant or heat. With this configuration, the lubricant can be easily distributed throughout the inside of the radial roller bearing, thus improving lubrication.

[0041] (3) The radial roller bearing according to (1) or (2), further comprising a cage having a plurality of pockets for accommodating the plurality of rollers, wherein the plurality of rollers are held by the molten retaining material and the cage. With this configuration, the amount of molten retaining material used can be reduced by holding the rollers in combination with the cage and the molten retaining material. In addition, the radial roller bearing 10 is less likely to deform even when external forces are applied during transportation, etc. Furthermore, when the radial roller bearing 10 is incorporated into a rotating machine, it becomes easier to restrict the axial movement of the rollers 100.

[0042] (4) A radial roller bearing according to any one of (1) to (3), further comprising a raceway ring having a raceway surface on its inner or outer circumferential surface. With this configuration, even in a radial roller bearing having a raceway ring, it is possible to prevent the rollers from falling out and to improve handling, load capacity, and lubricity.

[0043] (5) The melt-retaining material is formed in a ring shape so as to contact both axial ends of the plurality of rollers, and includes a pair of annular ends arranged coaxially, and a plurality of axially extending portions formed to connect the pair of annular ends in the axial direction and fill the circumferential gaps between the circumferentially adjacent rollers. The radial roller bearing according to any one of (1) to (4) is characterized in that. According to this configuration, the rollers can be stably held by the melt-retaining material.

[0044] As described above, various embodiments have been described while referring to the drawings. Needless to say, the present invention is not limited to such examples. It is obvious that those skilled in the art can conceive of various modification examples or correction examples within the scope described in the claims, and it is naturally understood that they also belong to the technical scope of the present invention. Also, within the scope not departing from the gist of the invention, the components in the above embodiments may be arbitrarily combined.

[0045] This application is based on a Japanese patent application (Japanese Patent Application No. 2024-189228) filed on October 28, 2024, the content of which is incorporated herein by reference.

[0046] 10 Radial roller bearing 20 Melt-retaining material 21 Annular end 23 Axially extending portion 25a Radial outer slit 25b Radial inner slit 25c Circumferential slit 27 Outer peripheral surface 29 Inner peripheral surface 50 Cage 51 Annular portion 53 Column portion 55 Pocket 70 Outer ring (raceway ring) 71 Raceway surface 200 Housing 300 Shaft

Claims

1. A radial roller bearing comprising: a plurality of rollers that roll on at least one of the inner surface of the housing and the outer surface of the shaft; and a meltable retaining material that holds the plurality of rollers in place before use and melts during use to enable the rolling of the plurality of rollers.

2. The radial roller bearing according to claim 1, characterized in that the meltable retaining material can be melted by a lubricant or heat.

3. The radial roller bearing according to claim 1, further comprising a retainer having a plurality of pockets for accommodating the plurality of rollers, wherein the plurality of rollers are held by the molten retaining material and the retainer.

4. The radial roller bearing according to claim 1, further comprising a raceway ring having a raceway surface on its inner or outer circumferential surface.

5. The radial roller bearing according to any one of claims 1 to 4, characterized in that the meltable retaining material comprises: a pair of annular ends formed in an annular shape so as to abut the axial ends of the plurality of rollers and arranged coaxially; and a plurality of axially extending portions formed to connect the pair of annular ends in the axial direction and to fill the circumferential gaps between adjacent rollers in the circumferential direction.

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