Cylindrical roller bearing

Abstract

The prevent invention relates to improving the precision of a roller guide surface of a column in a turned cage provided in a cylindrical roller bearing, and the outer diameter of the cage. A column (32) that partitions between rings (31) on both sides of a cage (30) has: a roller guide surface (32a) that is in contact, in the circumferential direction, with a cylindrical roller (20) rolling on a raceway surface (11); a fall stopper (32b) that restricts falling of the cylindrical roller (20) at a position different from the roller guide surface (32a) in the axial direction; an outer groove (32d) turned to a smaller diameter than the outer diameter of the ring (31); and an inner recessed surface (32f) turned to a larger diameter than the inner diameter of the ring (31). The fall stopper (32b) is continuous with the outer groove (32d) in the circumferential direction, and the inner recessed surface (32f) is located at a position intersecting the roller guide surface (32a) in the circumferential direction.

Description

Cylindrical roller bearings

[0001] The present invention relates to a cylindrical roller bearing having cylindrical rollers as rolling elements (here, the concept of cylindrical rollers also includes so-called needle rollers).

[0002] Conventionally, there is a cylindrical roller bearing that assembles an outer ring having a raceway surface and flanges on both sides, a number of cylindrical rollers, and a cage that maintains the circumferential spacing between these cylindrical rollers. There are several methods for manufacturing the cage, and the manufacturing method for the cage is determined mainly by the number of products required.

[0003] For example, to meet the large demand of hundreds of thousands of units per year, a welded cage is used, which is made by rolling a strip of steel into a ring and butting and welding both ends of the ring together.

[0004] In addition, pressed cages are used to meet the demand for several thousand units per year.

[0005] For demand of several hundred units per year, turned cages are used, in which the outer periphery of a cylindrical workpiece is turned to the outer diameter dimensions of the cage, and pocket holes are formed by radially punching the workpiece at multiple locations around its circumference.Turned cages are mainly used when the roller diameter of the cylindrical rollers is 5 mm or more, or when the imaginary circle diameter inscribed in the multiple cylindrical rollers in contact with the raceway surface of the outer ring is 100 mm or more, or when the cage is large in diameter.

[0006] This type of turned cage integrally includes rings on both sides and a plurality of pillars that space the rings at equal intervals in the circumferential direction. Cylindrical rollers are disposed between adjacent pillars in the circumferential direction. The rings have side end faces that extend between the adjacent pillars. The pillars have roller guide surfaces that contact the cylindrical rollers rolling on the raceway surface of the outer ring in the circumferential direction, stoppers that prevent the cylindrical rollers from falling out at positions axially different from the roller guide surfaces, and outer grooves that are turned along the circumferential direction to a diameter smaller than the outer diameter of the rings. The stoppers are continuous with the outer grooves of the pillars in the circumferential direction (see, for example, Patent Document 1).

[0007] The post roller guideway surface slides against the rolling surfaces of the cylindrical rollers under lubrication during operation of the cylindrical roller bearing. The post stop prevents the cylindrical rollers from falling out from between the flanges on both sides of the outer ring, maintaining the outer ring, multiple cylindrical rollers, and cage in an assembled state. The post outer groove is turned into the workpiece during cage manufacturing to form the stop at a position radially inward (toward the cage center axis) relative to the cylindrical rollers. After turning, a pocket hole is punched into the workpiece. It is preferable to remove sheared or fractured surfaces from the punched cross section of the workpiece, at least in the area where the roller guideway surface will be formed, to prevent damage to the rolling surfaces of the cylindrical rollers. This removal can be achieved by broaching. In broaching, the cutting edge of the broach is inserted in a radially aligned line relative to the pocket hole to remove the sheared or fractured surfaces, resulting in the formation of flat surfaces for the post roller guideway and the side end faces of the ring spanning between adjacent posts.

[0008] Japanese Utility Model Application Laid-Open Publication No. 5-22848

[0009] However, in the case of turned cages applied to large diameter sizes such as those described above, if the radial cross-sectional height of the cage is large and the outer diameter dimension of the cage is large, there is a problem that resistance is large when punching pocket holes or when broaching, making it difficult to ensure the accuracy of the pillar roller guide surfaces and the outer diameter of the cage.

[0010] In view of the above background, an object of the present invention is to improve the accuracy of the roller guide surfaces of the pillars of a turned cage provided in a cylindrical roller bearing and the accuracy of the cage outer diameter.

[0011] In order to solve the above-mentioned problems, the present invention employs Configuration 1, a cylindrical roller bearing comprising an outer ring having a raceway surface and opposite ribs, a plurality of cylindrical rollers, and a cage that maintains a circumferential gap between the cylindrical rollers, the cage integrally comprising opposite rings and a plurality of pillars that separate the opposite rings at equal intervals in the circumferential direction, the cylindrical rollers being arranged between adjacent pillars in the circumferential direction, the ring having side end faces that span the gap between the adjacent pillars, the pillars having roller guideways that are in circumferential contact with the cylindrical rollers rolling on the raceway surface, stoppers that prevent the cylindrical rollers from falling out at a position axially different from the roller guideways, and outer grooves that are turned to a diameter smaller than the outer diameter of the ring, the stoppers being circumferentially continuous with the outer groove, wherein the pillars have an inner concave surface that is turned to a diameter larger than the inner diameter of the ring, and the inner concave surface is formed at a position that intersects with the roller guideways in the circumferential direction.

[0012] The portion of the post that intersects with the roller guideway surface in the circumferential direction does not form a stop, and therefore, when manufacturing the cage, it is possible to lathe an inner concave surface into the workpiece so that the diameter is larger than the inner diameter of the ring. Furthermore, for the convenience of lathe-machining the outer groove and inner concave surface, pocket holes are punched into the workpiece after lathe machining. In other words, a cage having an inner concave surface is formed by punching pocket holes into a workpiece in which the cross-sectional shapes of the outer groove and inner concave surface have been lathe-machined. Therefore, lathe-machining the inner concave surface reduces resistance during punching of the pocket holes, and as a result, deformation during punching is suppressed. In other words, according to the above-mentioned configuration 1, the precision of the roller guideway surfaces of the posts of the turned cage and the outer diameter of the cage can be improved.

[0013] In the above-mentioned configuration 1, a configuration 2 can be adopted in which the outer groove of the pillar is formed in an axially intermediate portion of the pillar, and the inner concave surface of the pillar is formed between the ring on one side and the outer groove, and between the ring on the opposite side of the ring on the one side and the outer groove, respectively.

[0014] According to the above configuration 2, an inner concave surface is formed between the stopper at the axial middle part of the pillar and the rings on both sides, so that during the roller insertion process in which the cylindrical roller is forced to pass between the stoppers between adjacent pillars with the outer ring and cage radially stacked, the adjacent pillars pressed by the cylindrical roller are more likely to twist relative to the rings on both sides, making it possible to reduce the force required to press in the cylindrical roller.

[0015] In the above configuration 2, a configuration 3 can be adopted in which the entire pillar is provided to have a constant thickness.

[0016] According to the above configuration 3, during the roller insertion process, the entire pillar is easily twisted so as to open toward the outer ring, making it easier to press in the cylindrical roller.

[0017] In any one of the above configurations 1 to 3, a configuration 4 can be adopted in which the roller guide surface of the pillar is cut into a flat shape.

[0018] The broaching process, which cuts the roller guideway into a flat shape, is performed on the cross section where the pocket hole has been punched out. In other words, according to configuration 4, the resistance during broaching is reduced at the position that intersects with the roller guideway in the circumferential direction by the amount that is achieved by turning the inner concave surface, so the accuracy of the roller guideway and the outer diameter of the cage can be further improved.

[0019] In the above configuration 4, a configuration 5 can be adopted in which the drop stopper of the pillar has a circumferential end surface formed by a punched cross section.

[0020] The circumferential end faces of the stoppers are not parts that guide the cylindrical rollers when the cylindrical roller bearing is in operation, so there is no problem if they remain as sheared or broken surfaces. In other words, according to configuration 5, the circumferential end faces of the stoppers are not broached, which reduces the resistance during broaching, and therefore the precision of the roller guide surfaces and the outer diameter of the cage can be further improved.

[0021] In the above configuration 4 or 5, a configuration 6 can be adopted in which the pillar has a flank that is recessed in the circumferential direction from the roller guideway surface and extends between the ring and the roller guideway surface, the flank has a punched cross section, and the roller guideway is cut flat up to the flank.

[0022] When the roller guideway is extended to the ring, there is a concern that a step that cannot be completely removed by the broaching process will be generated at the corner between the roller guideway and the ring, which may interfere with the cylindrical roller. A flank that is recessed circumferentially from the roller guideway and extends between the roller guideway and the ring can be formed by punching a pocket hole. During broaching, it is possible to cut the roller guideway flat all the way to the flank so as not to generate the aforementioned step. In other words, according to configuration 6, while having a roller guideway without a step, the resistance during broaching is reduced because the flank is not broached, thereby further improving the accuracy of the roller guideway and the outer diameter of the cage.

[0023] In the above-described configuration 6, a configuration 7 can be adopted in which the side end surface of the ring is formed from a punched cross section.

[0024] When the above configuration 6 is adopted, it is not necessary to cut the roller guideway, the corners, and the side end faces of the ring all at once by broaching in order to avoid the occurrence of the above-mentioned steps at the corners of the roller guideway and the ring, and it is possible to form the side end faces of the ring with punched cross sections. According to the above configuration 7, since the side end faces of the ring are not broached, resistance during broaching is reduced, and it is possible to further improve the accuracy of the roller guideway and the outer diameter of the cage.

[0025] In any one of the above configurations 4 to 7, a configuration 8 can be adopted in which the pillar has an oil groove between the stopper and the roller guide surface that is recessed circumferentially further than the roller guide surface, and the oil groove has a punched cross section.

[0026] According to the above-mentioned configuration 8, an oil groove is present between the roller guideway surface and the stopper, which is recessed circumferentially from the roller guideway surface, and the oil groove can improve oil permeability in the radial direction. Furthermore, the oil groove, which is recessed circumferentially from the roller guideway surface and extends between the stopper and the roller guideway surface, can be formed by punching a pocket hole. In other words, according to the above-mentioned configuration 8, the oil groove is not broached, and therefore the resistance during broaching is reduced, and the precision of the roller guideway can be further improved.

[0027] As described above, by adopting the above configuration 1, the present invention can improve the accuracy of the roller guide surfaces of the pillars and the outer diameter of the cage in the turned cage provided in the cylindrical roller bearing.

[0028] 5 is a longitudinal sectional front view showing a cylindrical roller bearing according to a first embodiment of the present invention; FIG. 1 is a partial longitudinal sectional front view showing the appearance of the posts of the cage of FIG. 1 as viewed from the circumferential direction; FIG. 2 is a partial plan view development showing the cutting allowance of broaching when manufacturing the cage of FIG. 1; FIG. 3 is a partial plan view development showing the state after broaching; FIG. 4 is a longitudinal sectional front view showing a cage according to a second embodiment of the present invention;

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cylindrical roller bearing according to a first embodiment (hereinafter simply referred to as "this cylindrical roller bearing") as one example of the present invention will be described with reference to the accompanying drawings, FIGS. 1 to 4. FIG.

[0030] The cylindrical roller bearing shown in FIGS. 1 and 2 comprises an outer ring 10, a plurality of cylindrical rollers 20, and a cage 30 that holds these cylindrical rollers 20.

[0031] Here, the circumferential direction around the bearing center axis of this cylindrical roller bearing is called the "circumferential direction," the direction along the bearing center axis is called the "axial direction," and the direction perpendicular to the bearing center axis is called the "radial direction."

[0032] The outer ring 10 is a raceway ring having a raceway surface 11 and flanges 12 on both sides, which are seamlessly integrated on the inner periphery. The raceway surface 11 has a cylindrical surface shape along the circumferential direction. "Both sides" here means that they are arranged axially apart from each other, centered on the raceway surface 11. The flanges 12 on both sides each protrude radially inward beyond the raceway surface 11. The inner diameter surface of each flange 12 serves as a cage guide surface that guides the cage 30 radially.

[0033] The cylindrical rollers 20 are rolling elements having a cylindrical rolling surface that rolls on the raceway surface 11. The roller diameter of the cylindrical rollers 20 may be 5 mm or more, or may be less than 5 mm. The roller length of the cylindrical rollers 20 is, for example, 3 to 10 times the roller diameter of the cylindrical rollers 20.

[0034] The cage 30 is a bearing component that maintains the circumferential spacing between the cylindrical rollers 20. The cage 30 has rings 31 on both sides and a plurality of pillars 32 that separate the space between the rings 31 on both sides at equal intervals in the circumferential direction, all of which are integrated seamlessly. The cylindrical rollers 20 are arranged between the pillars 32 that are adjacent to each other in the circumferential direction.

[0035] This cylindrical roller bearing does not have an inner ring, and a mechanical element (not shown) such as a shaft having a raceway surface that is inscribed on a plurality of cylindrical rollers 20 is inserted into it. Note that this cylindrical roller bearing can also be modified to have an inner ring.

[0036] The cage 30 is made of metal.

[0037] The ring 31 is made of an annular portion that is continuous around the entire circumference. The ring 31 has a side end surface 31a that extends between adjacent columns 32. The side end surface 31a is cut into a flat shape that extends along the radial and circumferential directions.

[0038] The outer diameter surface of the ring 31 is guided in the radial direction by the inner diameter surface of the flange 12 that faces it in the radial direction.

[0039] As shown in FIGS. 1 and 2, the pillar 32 is substantially M-shaped when viewed in cross section in FIG. 1 and in the circumferential direction in FIG.

[0040] The pillar 32 has a roller guide surface 32a that contacts the cylindrical rollers 20 rolling on the raceway surface 11 of the outer ring 10 in the circumferential direction, a stopper 32b that prevents the cylindrical rollers 20 from falling off, an outer diameter surface 32c that is cut to the same diameter as the outer diameter of the ring 31, an outer groove 32d that is turned to a diameter smaller than the outer diameter of the ring 31, an inner diameter surface 32e that is turned to the same diameter as the inner diameter of the ring 31, and an inner concave surface 32f that is turned to a diameter larger than the inner diameter of the ring 31.

[0041] When the rolling cylindrical rollers 20 are skewed or advance / delay occurs during operation of this cylindrical roller bearing, the roller guide surface 32a comes into contact with the rolling surfaces of the cylindrical rollers 20 in the circumferential direction and guides the cylindrical rollers 20 in the circumferential direction.

[0042] The pair of stoppers 32b that face each other in the circumferential direction between adjacent columns 32 prevents the rolling surfaces of the cylindrical rollers 20 arranged between the adjacent columns 32 from dropping out from between the ribs 12 on both sides of the outer ring 10, and maintains the inscribed circle diameter for the plurality of cylindrical rollers 20 at a predetermined value or greater. The inscribed circle diameter is, for example, 100 mm or greater.

[0043] The pillar 32 has a roller guide surface 32a and a stopper 32b at one circumferential end and the other circumferential end of the pillar 32. The stopper 32b, the outer groove 32d, and the inner diameter surface 32e are each formed in an axially intermediate portion of the pillar 32. The roller guide surface 32a, the outer diameter surface 32c, and the inner concave surface 32f are each formed at one axial end and the other axial end of the pillar 32.

[0044] The roller guide surface 32a consists of a surface that has been cut into a flat shape. The pair of roller guide surfaces 32a that face each other in the circumferential direction between adjacent columns 32 are parallel to each other. The aforementioned guidance of the cylindrical rollers 20 by the roller guide surfaces 32a is more stable when it is performed at a position as close as possible to the central axis of the cylindrical rollers 20. For this reason, the roller guide surface 32a has a radial width that includes a position that faces circumferentially the central axis of the cylindrical rollers 20 that roll on the raceway surface 11 of the outer ring 10. A corner R surface for the purpose of stress relief is formed between the roller guide surface 32a and the corresponding side end face 31a.

[0045] The stopper 32b protrudes in the circumferential direction further than the roller guide surface 32a. The stopper 32b overlaps radially with the cylindrical roller 20 at a position closer to the radial inside of the central axis of the cylindrical roller 20 arranged between adjacent pillars 32. On the other hand, the roller guide surface 32a does not have a portion that overlaps radially with the cylindrical roller 20 at a position closer to the radial inside of the central axis of the cylindrical roller 20.

[0046] The outer diameter surface 32c is continuous with the corresponding ring 31 and has an arcuate shape extending in the axial and circumferential directions. The outer diameter surface 32c and the corresponding roller guide surface 32a intersect in the circumferential direction.

[0047] The outer groove 32d extends radially from the outer diameter surface 32c on both sides, with a groove depth extending circumferentially across the pillar 32. The groove bottom surface of the outer groove 32d is an arcuate surface extending circumferentially and axially. The groove side surfaces on both sides of the outer groove 32d are tapered, inclining from both edges of the groove bottom surface toward the radially outward direction so that the groove width increases axially.

[0048] The stopper 32b is a protrusion that includes the circumferential end of the groove bottom surface of the outer groove 32d, and is capable of radially contacting the cylindrical roller 20 at the circumferential end of this groove bottom surface.

[0049] The inner diameter surface 32e is an arcuate surface extending axially and circumferentially along the groove bottom surface of the outer groove 32d and having a width wider than that of the groove bottom surface of the outer groove 32d.

[0050] The inner concave surface 32f is recessed radially from the inner diameter surface 32e and extends circumferentially across the column 32. The inner concave surface 32f and the corresponding ring 31 form a groove extending circumferentially. The radial cross section of the ring 31 does not have a reduced portion due to the formation of the inner concave surface 32f, so the rigidity of the ring 31 can be maintained.

[0051] The bottom surface of the inner concave surface 32f is an arcuate surface extending in the circumferential and axial directions. The bottom surface of the inner concave surface 32f is located between the corresponding ring 31 and the outer groove 32d and intersects with the corresponding roller guide surface 32a in the circumferential direction. The portion of the inner concave surface 32f from the bottom surface to the inner diameter surface 32e is tapered and extends along the groove side surface of the corresponding side of the outer groove 32d.

[0052] By forming the outer groove 32d, the outer diameter surfaces 32c on both sides, the inner diameter surface 32e, and the inner concave surfaces 32f on both sides as described above, the entire substantially M-shaped pillar 32 is provided with a constant thickness t. Here, the reason why the entire pillar 32 is provided with a constant thickness t is to make it easier for the entire pillar 32 to twist toward the outer ring 10 relative to the rings 31 on both sides when the cylindrical rollers 20 are pressed between the stoppers 32b of the pair of adjacent pillars 32. This objective can be achieved even if the entire pillar 32 does not have to have a strictly constant thickness t, as long as it has a substantially constant thickness. Therefore, in this invention, "the pillar is provided with a constant thickness" includes cases where the thickness varies to alleviate stress at the edges and corners of the pillar or due to dimensional tolerances in manufacturing the cage, and specifically includes a range in which the maximum thickness of the pillar 32 is up to 1.1 times the minimum thickness of the pillar 32.

[0053] Furthermore, if the entire approximately M-shaped pillar 32 is made to have a constant thickness t, the retainer 30 will be as lightweight as a pressed retainer made by pressing a single metal plate into a similar approximately M shape, and will therefore be able to be used for high-speed rotation.

[0054] In the manufacturing process for the above-mentioned retainer 30, a cylindrical workpiece is used as the raw material, and the following steps are carried out: turning, in which the workpiece is cut into the required shape by the rotational movement of the workpiece and the feed movement of a bit within a plane including the rotation axis; punching, in which pocket holes are made in the turned workpiece using a press; and broaching, in which the required portions of the punched cross section formed in the workpiece by the punching process are cut.

[0055] In the turning process, first, a process of turning the outer diameter surface of the workpiece and a process of turning the inner diameter surface of the workpiece are carried out to create the raceway surface. At this time, the outer diameter surface of the workpiece is turned into a cylindrical surface having the same outer diameter dimensions as the cage. Also, the inner diameter surface of the workpiece is turned into a cylindrical surface having the same inner diameter dimensions as the cage.

[0056] Thereafter, a step of turning an outer circumferential groove Go around the entire outer periphery of the workpiece W (see FIG. 3 ) at a position that divides the outer diameter surface of the workpiece W into two outer diameter surfaces So on both sides, and a step of turning an inner circumferential groove Gi on both sides of the inner diameter surface of the workpiece W are carried out. In the step of turning the outer circumferential groove Go, the entire periphery of the region corresponding to the outer groove of the pillar is turned to the cross-sectional shape of the outer groove. In the step of turning the inner circumferential groove Gi, the entire periphery of the region corresponding to the inner concave surface of the pillar is turned to the cross-sectional shape of the inner concave surface.

[0057] After these turning processes have been completed, the workpiece W is subjected to punching to form pocket holes. In this punching process, the workpiece W is punched from the outer periphery to the inner periphery using a press, forming a punched cross section Er shown by the solid line in Figure 3. The punched cross section Er includes a shear surface and a fracture surface, and forms the edge of the pocket hole. In the workpiece W, punched cross sections Er of a plurality of pocket holes are formed at equal intervals in the circumferential direction.

[0058] Here, the larger the cross-sectional area punched out from the thicker portion of the workpiece W, the greater the resistance during punching, and therefore the greater the load applied to the workpiece W from the press. This load distorts the workpiece W, disrupting the surface shape and surface roughness of the punched cross section Er and the surface shape of the outer diameter surface So of the workpiece W. As a result, the accuracy of the punched cross section Er and the outer diameter of the outer diameter surface So is likely to decrease. By performing pocket hole drilling on the workpiece W with the inner circumferential groove Gi turned, the cross-sectional area punched out from the thicker portion is reduced, reducing the resistance during punching, and thereby improving the accuracy of the punched cross section Er and the outer diameter of the outer diameter surface So (corresponding to the outer diameter of the finished cage). Here, if the accuracy of the punched cross section can be sufficiently improved by suppressing the resistance caused by turning the inner circumferential groove Gi, it is also possible to use a portion of the punched cross section as a roller guide surface for the finished cage.

[0059] However, because the roller guideway surface of the cage is the portion that comes into sliding contact with the rolling surfaces of the cylindrical rollers, it is undesirable for it to include a rough fracture surface, and it is preferable to form the roller guideway surface by further cutting the punched cross section. In the example of Fig. 3, in order to leave a cutting allowance CA (the area shown by the two-dot chain line in Fig. 3) for creating the protruding shapes of the roller guideway surface and the pillar stopper by cutting, the punched cross section Er is formed into a rectangular shape in plan view, leaving the cutting allowance CA to be removed by broaching.

[0060] The broaching is performed for each pocket hole. In this process, a single insertion of the broach into the pocket hole removes the cutting allowance CA on both sides of the rectangular punched cross section Er, forming the roller guide surfaces 32a on both the top, bottom, left, and right sides (a total of four roller guide surfaces 32a) in FIG. 4 , as well as the left and right side end surfaces 31a. This also results in the formation of the axial end faces of the stopper 32b, one circumferential end edge of the outer diameter surface 32c, one circumferential end edge of the outer groove 32d, one circumferential end edge of the inner diameter surface 32e, and one circumferential end edge of the inner concave surface 32f, all of which are shown in FIGS. 1, 2, and 4. When the punched cross sections of all the pocket holes in the workpiece are broached, the overall shape of the cage 30 shown in FIGS. 1 and 2 is completed.

[0061] Here, the larger the area cut by the broach at the thicker portion of the punched cross section Er in Figure 3, the greater the resistance during cutting, and therefore the greater the local load that the broach applies to the punched cross section Er at one point on the workpiece W. This load causes the workpiece W to distort and deform, disrupting the surface shape and surface roughness of the roller guide surfaces 32a being cut and disrupting the surface shape of the outer diameter surface So of the workpiece W. As a result, the accuracy of the finished roller guide surfaces 32a and the outer diameter of the cage 30 shown in Figures 2 and 4 (the circumscribed circle diameter for the outer diameter surfaces 32c of the multiple pillars 32, and the outer diameter of the outer diameter surface So of the ring 31) is likely to decrease.

[0062] By performing pocket hole drilling on the workpiece W in which the inner circumferential groove Gi has been turned, the accuracy of the punched cross section Er and the outer diameter of the outer diameter surface So (corresponding to the outer diameter of the finished cage) is improved accordingly, which also improves the accuracy of the cutting allowance CA. Furthermore, by performing broaching on the workpiece W in which the inner circumferential groove Gi has been turned, the area of ​​the thick portion of the cutting allowance CA is reduced and the resistance during cutting is reduced, which in turn improves the accuracy of the finished roller guide surfaces 32a and the outer diameter of the cage 30.

[0063] In the example of FIG. 3, in order to avoid the occurrence of steps at the corners between the roller guide surface and the ring that cannot be completely removed by broaching, a cutting allowance CA is provided so that the roller guide surface 32 a, the corners, and the side end surface 31 a of the ring 31 are cut all at once by broaching.

[0064] Furthermore, the circumferential end faces of the stoppers 32b are not portions that contact and guide the rolling surfaces of the cylindrical rollers 20, and therefore do not need to be finished with high precision by broaching. In order to reduce resistance during broaching, no cutting allowance CA is provided in the portions of the intermediate long sides of the punched cross section Er that will become the circumferential end faces of the stoppers. In other words, the circumferential end faces of the stoppers 32b shown in Figures 1, 2 and 4 are made up of punched cross sections (corresponding to the intermediate long sides of the punched cross section Er in Figure 3).

[0065] This cylindrical roller bearing (see Figures 1 to 4) is as described above, and comprises an outer ring 10 having a raceway surface 11 and flanges 12 on both sides, a plurality of cylindrical rollers 20, and a cage 30 that maintains the circumferential spacing between the cylindrical rollers 20, the cage 30 integrally having rings 31 on both sides and a plurality of pillars 32 that separate the space between these rings 31 on both sides at equal intervals in the circumferential direction, the cylindrical rollers 20 being arranged between the pillars 32 adjacent to each other in the circumferential direction, 31 has a side end surface 31a extending between adjacent pillars 32, and the pillars 32 have a roller guide surface 32a that contacts the cylindrical rollers 20 rolling on the raceway surface 11 in the circumferential direction, a drop stopper 32b that prevents the cylindrical rollers 20 from falling off at a position axially different from the roller guide surface 32a, and an outer groove 32d (corresponding to a part of the outer circumferential groove Go of the workpiece W) that is turned to a diameter smaller than the outer diameter of the ring 31, and the drop stopper 32b is continuous with the outer groove 32d in the circumferential direction.

[0066] In particular, this cylindrical roller bearing has an inner concave surface 32f (corresponding to part of the inner circumferential groove Gi of the workpiece W) that has been turned on the post 32 to a diameter larger than the inner diameter of the ring 31, and the inner concave surface 32f is formed at a position that intersects with the roller guideway surface 32a in the circumferential direction, so that the resistance when punching the pocket holes is reduced by the amount that the inner concave surface 32f has been turned, and as a result, deformation during punching is suppressed. Therefore, this cylindrical roller bearing can improve the precision of the roller guideway surface 32a of the post 32 of the turned cage and the outer diameter of the cage.

[0067] Furthermore, in this cylindrical roller bearing, the outer groove 32d of the pillar 32 is formed in the axial middle of the pillar 32, and the inner concave surface 32f of the pillar 32 is formed between the ring 31 on one side and the outer groove 32d, and between the ring 31 on the opposite side of the ring 31 on that side and the outer groove 32d, respectively.Therefore, during the roller insertion process in which the cylindrical rollers 20 are forced to pass between the stoppers 32b of adjacent pillars 32 with the outer ring 10 and the retainer 30 radially stacked, the adjacent pillars 32 pressed by the cylindrical rollers 20 are more likely to twist relative to the rings 31 on both sides, and the force required to press in the cylindrical rollers 20 can be reduced.

[0068] Furthermore, in this cylindrical roller bearing, the entire pillars 32 are provided with a constant thickness t, so that during the roller insertion process described above, the entire adjacent pillars 32 tend to twist open toward the outer ring 10, making it easier to press in the cylindrical rollers 20.

[0069] Furthermore, in this cylindrical roller bearing, the roller guide surface 32a of the pillar 32 is cut into a flat shape, and the resistance during broaching is reduced at the position where it intersects with the roller guide surface 32a in the circumferential direction by the amount that the inner concave surface 32f is turned, thereby further improving the accuracy of the roller guide surface 32a and the outer diameter of the retainer 30.

[0070] Furthermore, this cylindrical roller bearing has a circumferential end face consisting of the punched cross section (part of the punched cross section Er of the workpiece W) of the drop stopper 32b of the pillar 32, and since the circumferential end face of the drop stopper 32b is not broached, resistance during broaching is reduced, thereby enabling further improvement in the accuracy of the roller guide surface 32a and the outer diameter of the retainer 30.

[0071] A second embodiment of the present invention will be described with reference to Figures 5 and 6. Note that only differences from the first embodiment will be described here, and the same reference numerals will continue to be used for components corresponding to those in the first embodiment.

[0072] 5, the pillar 32 according to the second embodiment has a flank 32g that is recessed in the circumferential direction from the roller guide surface 32a and extends between the roller guide surface 32a and the ring 31. The flank 32g and the side end surface 31a of the ring 31 are formed by punching cross sections.

[0073] As shown in Figure 6, in the punching process for the pocket hole, a punched cross section Er is formed, which has flank-like portions Ec at the four corners of the rectangular shape, recessed in the circumferential direction from the rectangular long-side straight portion. The cutting allowance CA is provided only in the region from the flank-like portion Ec toward the center in the axial direction. The flank-like portion Ec is composed of the region that becomes the flank 32g shown in Figure 5, the region that becomes the side end face 31a of the ring 31, and the axial end face of the cutting allowance CA shown in Figure 6. Because the flank-like portion Ec is provided and the cutting allowance CA is spaced apart from the corners of the punched cross section Er, it is possible to cut the roller guide surface 32a shown in Figure 5 flat up to the flank 32g so as not to leave a step that cannot be completely removed by the broach at the corner between the roller guide surface 32a and the side end face 31a of the ring 31. When the cutting allowance CA is removed by broaching, the four flanks 32g shown in FIG. 5 are formed, and the roller guide surfaces 32a are cut flat up to the flanks 32g, while the side end surfaces 31a of the ring 31 remain as the short sides of the punched cross section Er in FIG. 6.

[0074] In this way, in the cylindrical roller bearing according to the second embodiment (see FIGS. 5 and 6), in particular, post 32 has flank 32g that is recessed in the circumferential direction more than roller guide surface 32a, extending between ring 31 and roller guide surface 32a, and flank 32g consists of a punched-out cross section (corresponding to a part of flank surface portion Ec), and roller guide surface 32a is cut flat up to flank 32g. Therefore, while having roller guide surface 32a without the aforementioned remaining step, flank 32g is not broached, and as such, resistance during broaching is reduced, and the precision of roller guide surface 32a and the outer diameter of the cage can be further improved.

[0075] Furthermore, in the cylindrical roller bearing according to the second embodiment, the side end surface 31 a of the ring 31 consists of a punched cross section (corresponding to a part of the punched cross section Er), and therefore the side end surface 31 a of the ring 31 is not broached, thereby reducing the resistance during broaching, and thereby enabling further improvement in the accuracy of the roller guide surface 32 a and the outer diameter of the cage.

[0076] A third embodiment of the present invention will be described with reference to Figures 7 to 9. Note that the third embodiment is a further modification of the second embodiment, and therefore only differences from the first and second embodiments will be described here, and the same reference numerals will continue to be used for components corresponding to those of the first and second embodiments.

[0077] 7 and 8, the pillar 32 according to the third embodiment has oil grooves 32h on both sides of the stopper 32b, which are recessed in the circumferential direction from the roller guide surface 32a between the stopper 32b and the roller guide surface 32a. Note that, since the oil groove 32h is disposed between the stopper 32b and the roller guide surface 32a, it traverses in the radial direction between the tapered portion of the outer groove 32d and the tapered portion of the inner concave surface 32f.

[0078] The oil groove 32h forms a space between the cylindrical rollers 20 even when the roller guide surface 32a and the cylindrical rollers 20 are in contact during operation of the cylindrical roller bearing. During operation of the bearing, lubricating fluids such as lubricating oil and grease inside the bearing tend to flow toward the outer ring due to the influence of centrifugal force. The lubricating fluid that enters the space between the pillar 32 and a mechanical element (not shown) such as a shaft that is inscribed in the multiple cylindrical rollers 20 has relatively little chance of passing through between the stopper 32b and the cylindrical rollers 20 or between the roller guide surface 32a and the cylindrical rollers 20 to the outer ring side, but it can flow toward the outer ring side through the space formed between the oil groove 32h and the cylindrical rollers 20.

[0079] The oil groove 32h and the end faces on both sides of the stopper 32b in the axial direction are formed by punched cross sections.

[0080] As shown in Figure 9, the punching process for the pocket hole forms a punched cross section Er having four grooves Ed recessed in the circumferential direction from the rectangular long-side straight portion. The cutting allowance CA is provided only in the long-side region between the flank-shaped portion Ec and the grooves Ed. The grooves Ed are composed of the region that becomes the oil groove 32h shown in Figures 7 and 8, the region that becomes the axial end face of the stopper 32b, and the axial end face of the cutting allowance CA shown in Figure 9. When the cutting allowance CA is removed by broaching, the four oil grooves 32h shown in Figures 7 and 8 are formed, and a planar roller guide surface 32a is formed between the oil groove 32h and the flank 32g, while the axial end face of the stopper 32b remains as part of the grooves Ed in the punched cross section Er shown in Figure 9.

[0081] In this way, in the cylindrical roller bearing according to the third embodiment, pillar 32 has oil groove 32h between stopper 32b and roller guide surface 32a, which is recessed circumferentially further than roller guide surface 32a, and oil groove 32h consists of a punched-out cross section (corresponding to a part of groove portion Ed of punched cross section Er), so that oil groove 32h can improve oil permeability in the radial direction, and because oil groove 32h is not broached, resistance during broaching is reduced, so the precision of roller guide surface 32a can be further improved.

[0082] A fourth embodiment of the present invention will be described with reference to Figures 10 and 11. Note that the fourth embodiment is a further modification of the third embodiment, so only differences from the third embodiment will be described here, and the same reference numerals will continue to be used for components corresponding to those of the third embodiment.

[0083] As shown in Fig. 10 , the cylindrical roller bearing according to the fourth embodiment has no flank (see the four flanks 32g shown in Fig. 8 ) formed between the roller guide surface 32a and the side end face 31a of the ring 31. In line with this change, a cutting allowance CA is provided in the pocket hole punching step as shown in Fig. 11 , and this cutting allowance CA is cut all at once in broaching, thereby preventing the formation of steps that cannot be completely removed by broaching at the corners between the roller guide surface 32a and the side end face 31a of the ring 31 as shown in Fig. 10 . The cylindrical roller bearing according to the fourth embodiment improves oil permeability by the oil groove 32h, while, because the oil groove 32h is not broached, the resistance during broaching can be made smaller than that during broaching with the cutting allowance CA in the first embodiment shown in Fig. 3 .

[0084] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0085] 10 outer ring 11 raceway surface 12 flange 20 cylindrical roller 30 cage 31 ring 31a side end face 32 pillar 32a roller guideway surface 32b stopper 32d outer groove 32f inner concave surface 32g relief surface 32h oil groove Er punched cross section (punched cross section) CA cutting allowance Go outer circumferential groove Gi inner circumferential groove

Claims

1. A cylindrical roller bearing comprising an outer ring having a raceway surface and flanges on both sides, a plurality of cylindrical rollers, and a cage that maintains a circumferential gap between the cylindrical rollers, wherein the cage integrally has opposite rings and a plurality of pillars that divide the space between the opposite rings at equal intervals in the circumferential direction, the cylindrical rollers are arranged between adjacent pillars in the circumferential direction, the ring has side end faces that extend between the adjacent pillars, and the pillars have roller guideways that are in circumferential contact with the cylindrical rollers rolling on the raceway surface, stoppers that prevent the cylindrical rollers from falling out at a different axial position from the roller guideways, and outer grooves that are turned to a diameter smaller than the outer diameter of the ring, and the stoppers are circumferentially continuous with the outer groove, wherein the pillars have an inner concave surface that is turned to a diameter larger than the inner diameter of the ring, and the inner concave surface is formed at a position that intersects with the roller guideways in the circumferential direction.

2. A cylindrical roller bearing as set forth in claim 1, wherein the outer groove of the pillar is formed in an axially intermediate portion of the pillar, and the inner concave surface of the pillar is formed between the ring on one side and the outer groove, and between the ring on the opposite side to the ring on the one side and the outer groove.

3. A cylindrical roller bearing according to claim 2, wherein the entire pillar has a constant thickness.

4. A cylindrical roller bearing according to any one of claims 1 to 3, wherein the roller guide surface of the pillar is cut into a flat surface.

5. A cylindrical roller bearing according to claim 4, wherein said detent of said post has a circumferential end face formed of a stamped cross section.

6. A cylindrical roller bearing as set forth in claim 4 or 5, wherein the pillar has a flank that extends between the roller guideway surface and the ring and is recessed in the circumferential direction from the roller guideway surface, the flank having a punched cross section, and the roller guideway being cut flat up to the flank.

7. A cylindrical roller bearing according to claim 6, wherein said side end surfaces of said rings are formed from stamped cross sections.

8. A cylindrical roller bearing as set forth in any one of claims 4 to 7, wherein the pillar has an oil groove recessed circumferentially further than the roller guideway between the stopper and the roller guideway, the oil groove having a punched cross section.

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