Roller bearing

Abstract

A roller bearing (1) is provided with a plurality of rollers (3) and a retainer (2) for holding the rollers (3). The retainer (2) has a pair of annular parts (4, 4) facing both axial-direction ends of each roller (3), and a plurality of column parts (5) installed across the outer diameter parts of the pair of annular parts (4, 4) and provided at regular intervals in the circumferential direction. The retainer (2) has a welded part (We) in which one location in the circumferential direction in each annular portion (4) is connected by welding. The inner-diameter part of each annular part (4) is provided with a roller-retaining claw (6) that prevents the roller from slipping out to the inner-diameter side of the retainer. The roller-retaining claws (6) are bent piece-shaped roller-retaining claws provided in the portions between adjacent rollers (3, 3) in the inner-diameter parts of the annular parts (4).

Description

Roller bearings Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2024-092929, filed June 7, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a roller bearing used in general industrial machinery and the like, and in particular to a roller bearing used in applications requiring space saving and high load capacity, such as automobile mechanism parts and robot mechanism parts.

[0003] In a roller and cage assembly consisting of a cage and rollers, a technology has been proposed in which the cage has roller retainer claws that protrude toward the inner diameter side of the annular part and prevent the rollers from slipping out toward the inner diameter side (Patent Document 1). All parts of the cage, except for the roller retainer claws on the inner diameter side, are heat treated by induction hardening and induction tempering. The roller retainer claws are also subjected to special treatments such as carburization prevention.

[0004] Japanese Patent Application Laid-Open No. 2006-90428

[0005] In the above-mentioned conventional technology, the roller retaining claws are bent axially inward after the rollers are assembled into a heat-treated cage, which makes assembly less easy than inserting the roller assembly by press-fitting it from the inner diameter side of the cage.

[0006] In conventional techniques in which the roller retaining claws are bent after the rollers are inserted, a guide jig may be required to prevent the rollers from shifting toward the inner diameter at the inscribed portion of the roller when the roller retaining claws are bent. This creates the problem that the inner diameter dimension of the annular portion other than the roller retaining claws bent toward the inner diameter is at its smallest before the roller retaining claws are bent, limiting the inner diameter dimension. Furthermore, conventional techniques require special treatments, such as carburization prevention treatment, for the roller retaining claws, which increases the number of processing steps.

[0007] An object of the present invention is to provide a roller bearing that can be easily assembled and that can reduce the number of processing steps.

[0008] The roller bearing of the present invention comprises a plurality of rollers and a retainer that retains these rollers, the retainer having a pair of annular portions facing both axial ends of each of the rollers, and a plurality of pillar portions that are installed across the outer diameter portions of the pair of annular portions and are arranged at regular intervals in the circumferential direction, the retainer having a welded portion where each of the annular portions is connected by welding at one point in the circumferential direction, and is characterized in that the inner diameter portion of each of the annular portions is provided with a roller retaining claw that prevents the rollers from slipping out toward the inner diameter side of the retainer.

[0009] This configuration minimizes the number of parts required, down to the rollers and cage, making it possible to achieve a high load capacity in a limited space. The cage is connected by welding at one circumferential point on each annular portion. Therefore, after the cage is completed, after bending the roller retaining claws, heat treatment can be performed on the roller retaining claws, eliminating the need for special treatments such as carburization prevention.

[0010] Furthermore, because each annular portion is connected by welding at one point in the circumferential direction, the rollers are inserted into the completed cage after bending the roller retaining claws and then pressed in from the inner diameter side of the roller retaining claws, causing the roller retaining claws to elastically deform. This makes it easier to assemble the roller bearing than with conventional techniques in which the roller retaining claws are bent after the rollers are inserted, and by eliminating the need for the aforementioned guide jigs and the like, there are no restrictions on the inner diameter of the annular portion, allowing for greater freedom in design.

[0011] The roller bearing may include either an inner ring or an outer ring, or both. The cage described above can be applied to such various roller bearings.

[0012] The roller retaining claws may be bent piece-shaped roller retaining claws provided between adjacent rollers on the inner diameter portion of the annular portion. In this case, by minimizing the axial length of the roller retaining claws, it is possible to ensure a wider exposed portion of the rollers on the inner diameter side than in the prior art, thereby improving oil permeability.

[0013] The angle of the roller retainer claws relative to the width surface of the cage may be 70° or more and 90° or less. The width surface of the cage is synonymous with the outer surface of the annular portion. When the rollers are press-fitted from the inner diameter side of the cage, the rollers are more easily press-fitted with a stable posture if the roller retainer claws and the central axes of the rollers are parallel. Furthermore, the inner diameter of the annular portion bent toward the inner diameter is preferably as small as possible to increase the ring rigidity of the cage, and it is advantageous to bend the roller retainer claws to an extent that they are parallel to the central axes of the rollers. In terms of practical management, it is easier to express the roller retainer claws as angles relative to the width surface of the cage, so for the two reasons mentioned above, it is preferable that the angle of the roller retainer claws relative to the width surface of the cage be 90°.

[0014] Considering springback, bending the roller retainer claws to 90 degrees requires pressing from the inner diameter side toward the radially outward direction. This requires a complex die structure, which is disadvantageous in terms of cost, so bending the roller retainer claws in the axial direction is also acceptable. For example, it is more economical to use a cylindrical die to bend all the roller retainer claws around the circumference from the axial direction at once. As mentioned above, considering springback of the roller retainer claws, it is realistic to set the angle of the roller retainer claws relative to the width surface of the cage to be between 70° and 90°.

[0015] The tip end of the roller retaining claw may be positioned axially inward from the roller end face by 2.5 x the axial chamfer dimension of the roller to 0.25 x the roller length. In this application, chamfering refers to a configuration in which an oblique surface is added to the corner where two surfaces intersect. This definition conforms to JIS B 3401. Chamfering can be formed not only by cutting or the like, but also by press working or the like. The axial chamfer of the roller refers to the length of the axially extending portion of the chamfer connecting the outer diameter surface and width surface of the roller.

[0016] This configuration not only prevents the rollers from falling off, but also improves the workability of the roller retaining claws and prevents a decrease in oil permeability. If the tip of the roller retaining claw is located axially inward from the roller end face by more than 25% of the roller length, this may result in a decrease in oil permeability. If the tip of the roller retaining claw is located axially inward from the roller end face at a position less than 2.5 times the axial chamfer dimension of the roller, it may be difficult to bend the roller retaining claws due to their short length.

[0017] The radial positions of the roller retaining claws may satisfy the following formulas: (roller circumscribing circle diameter - cage outer diameter) / 2 < radial clearance between roller and roller retaining claw (roller circumscribing circle diameter - cage outer diameter) / 2 < cage inner diameter - roller inscribing circle diameter

[0018] This configuration can prevent excessive contact between the rollers and the roller retainer claws without interfering with the drive of the cage. If the radial clearance between the rollers and the roller retainer claws is (roller circumscribing circle diameter - cage outer diameter) / 2 ≥ 0, the rollers and roller retainer claws will come into excessive contact during operation, scraping off the lubricant on the roller surface and applying a load to the roller retainer claws, requiring consideration of the strength of the roller retainer claws. If (roller circumscribing circle diameter - cage outer diameter) / 2 ≥ 0, the roller retainer claws may come into contact with the shaft, interfering with the drive of the cage.

[0019] The roller retaining claw may have a rectangular cross section when cut along an imaginary plane perpendicular to the axial direction, in which case plastic deformation of the outer diameter portion of the roller retaining claw, which affects the clearance between the roller and the roller retaining claw, can be reduced.

[0020] The axial chamfer dimension of the roller may be 2.5% or more and 30% or less of the roller diameter. In this case, the degree of freedom in setting the axial length of the roller retaining pawl can be increased, and the load capacity can be improved. If the axial chamfer dimension of the roller is less than 2.5% of the roller diameter, the axial length of the roller retaining pawl that retains the roller chamfered portion is limited. If the axial chamfer dimension of the roller is more than 30% of the roller diameter, the load capacity decreases.

[0021] The cage may have a carbon content of 0.08 to 0.20 mass% and may be subjected to carburizing heat treatment. This configuration ensures good hardenability and weldability for the cage. Roller bearings are sometimes used in double rows, arranged adjacent to each other in the axial direction. In this case, a thrust component force (hereinafter referred to as "induced thrust force") is generated in each roller bearing during operation due to roller skew. Therefore, sliding friction occurs as the roller bearings rotate while rubbing against each other across their width surfaces, making it essential to ensure surface hardness against wear. Furthermore, toughness is required to withstand stresses generated when the rollers are press-fitted and when the roller retaining claws are bent. To satisfy these conditions, the cage is preferably made of a material that can be carburized.

[0022] The roller retaining claws may have a tip width smaller than a base width, in which case the roller retaining claws can be prevented from being plastically deformed when the rollers are press-fitted, and the rollers can be prevented from falling out to the inner diameter side.

[0023] The cage may be plated or blackened, which can prevent a decrease in corrosion resistance of the welded portion and improve the sliding properties of the cage guide surfaces and the like.

[0024] A cross section of the pillar portion taken along an imaginary plane perpendicular to the axial direction may include an inclined surface that slopes so that the pillar portion width decreases radially inward, thereby ensuring the cross-sectional area and strength of the pillar portion in a limited space.

[0025] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0026] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation, and should not be used to define the scope of the present invention, which is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.

[0027] 6A and 6B are perspective views of a roller bearing according to a first embodiment of the present invention; a longitudinal sectional view of the roller bearing; a partially enlarged view showing the amount of interference between the roller and roller retention claws of the roller bearing; a view schematically showing the machining process of the cage of the roller bearing; a view showing the forming-punching process of the roller retention claws of the cage; a view showing the bending process of the roller retention claws; a cross sectional view of a main part of the roller bearing; a partially enlarged view of part VII of FIG. 6; a longitudinal sectional view showing the angle of the roller retention claws of the cage; a longitudinal sectional view showing a modified example in which the angle of the roller retention claws of the cage is changed; a longitudinal sectional view showing an enlarged tip position of the roller retention claws of the cage; a cross sectional view of a main part showing a first radial position of the roller retention claw; a cross sectional view of a main part showing a second radial position of the roller retention claw; a longitudinal sectional view showing the radial dimension of the width face of the cage; a cross sectional view of a main part showing the plate thickness of the roller retention claw; a partially enlarged view showing the amount of interference between the roller and roller retention claws when the tip end of the roller retention claw is not tapered. Fig. 1 is a partially enlarged view showing the amount of interference between the roller and roller retaining claws when the tip end of the roller retaining claw is tapered. Fig. 2 is a partially enlarged view showing the position of maximum interference amount of the roller and roller retaining claws. Fig. 3 is a cross-sectional view of a main part showing the cross-sectional shape of a pillar portion of a conventional cage. Fig. 4 is a cross-sectional view of a main part showing the cross-sectional shape of a pillar portion of a roller bearing according to a second embodiment of the present invention. Fig. 5 is a cross-sectional view of a main part showing a modified example of the pillar portion. Fig. 6 is a longitudinal sectional view of a roller bearing according to a third embodiment of the present invention.

[0028] [First embodiment] A roller bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 15. This roller bearing is used in applications that require space saving and high load capacity, such as automotive mechanism parts, robot mechanism parts, etc. The roller bearing can also be used in applications other than those mentioned above.

[0029] <Overall structure of roller bearing> As shown in Figure 1, a roller bearing 1 comprises a cage 2 and a plurality of rollers 3. A roller bearing 1 that is not provided with inner and outer rings is also called a caged roller 1. The roller bearing 1 is used in a single row or a double row (not shown). The cage 2 that holds the plurality of rollers 3 has a pair of annular portions 4, 4 and a plurality of pillar portions 5. The pair of annular portions 4, 4 face both axial ends of each roller 3, in other words, they face each other but are spaced apart in the axial direction.

[0030] As shown in Figure 2, a plurality of column portions 5 are installed across the outer diameter portions of a pair of annular portions 4, 4 and are provided at regular intervals in the circumferential direction, and pockets Pt into which rollers 3 are inserted are formed between adjacent column portions 5, 5 in the circumferential direction. The column portions 5 are provided with a diameter larger than the pitch circle diameter PCD of the roller arrangement and extend in the axial direction. Roller retaining claws 6, which will be described later, are provided on the inner diameter portion of each annular portion 4. The rollers 3 are made of, for example, bearing steel or the like and are, for example, needle rollers. However, the rollers 3 may also be cylindrical rollers.

[0031] In this specification, "axial direction" refers to the direction along the axis AX of the roller bearing 1 or the direction parallel to the axis AX. The direction perpendicular to the axis AX is called the "radial direction," and the circumferential direction around the axis AX is called the "circumferential direction." The side facing the axis AX is called the "inner diameter side," and the side away from the axis AX is called the "outer diameter side." Note that the units in the mathematical formulas described below are "mm" unless otherwise specified.

[0032] <Basic structure of cage (1) to (4)> (1) The roller retaining claws 6 of the cage 2 prevent the rollers 3 from slipping out towards the inner diameter side of the cage. The roller retaining claws 6 are bent piece-shaped roller retaining claws provided in the area between adjacent rollers on the inner diameter part of the annular part 4. The roller retaining claws 6 have a root part 6a that is connected to the inner diameter part of the annular part 4 and slopes axially inward as it approaches the inner diameter side, and a tip part 6b that is connected to this root part 6a and extends axially inward. The roller retaining claws 6 are sometimes simply referred to as retaining claws 6.

[0033] (2) In order to increase the strength of the retention claws 6 of the cage 2 even in a limited space, it is preferable that the retention claws 6 have a larger cross section. To achieve this, the cross section of the retention claws 6 can be shaped so that it is largest at the root portion 6a bent inward toward the inner diameter and becomes smaller toward the tip portion 6b. This cross section is a cross section (transverse cross section in Figure 6) of the retention claws 6 cut by an imaginary plane perpendicular to the axial direction. Furthermore, the contact points when press-fitting the rollers 3 and when preventing the rollers 3 from falling out after assembly of the roller bearing are the chamfered portions 3a of the rollers 3 and the retention claws 6. This allows the cross section of the retention claws 6 to be made even larger.

[0034] (3) Amount of interference between rollers and retaining claws In (2) above, the explanation was given on the assumption that the axial center of cage 2 and the axial center of rollers 3 are parallel when rollers 3 are press-fitted into cage 2. However, rollers 3 may be press-fitted by inserting rollers 3 from one axial direction, that is, the outer diameter side of one of retaining claws 6 on the left or right side in Figure 2, from an oblique direction on the inner diameter side, and then press-fitting rollers 3 only from the retaining claw 6 on the other axial direction.

[0035] With this method of press-fitting rollers 3 only from the other axial retaining claw 6, as shown in Figure 3, the interference amount IF between rollers 3 and retaining claws 6 that allows rollers 3 to be press-fitted can be made larger on the side of one axial retaining claw 6, reducing the risk of roller separation after assembly. The interference amount IF is the sum of the elastic displacement amounts of retaining claws 6 and rollers 3. With the above-mentioned method, the shapes and dimensions of the annular portions 4 and retaining claws 6 provided on the inner diameter sides on the left and right sides in Figure 2 do not necessarily have to be identical on the left and right, which increases the degree of freedom in setting the shapes and dimensions.

[0036] (4) Regarding Welded Portions, etc. As shown in FIG. 4, the cage 2 has a welded portion We (FIG. 4(f)), where each annular portion 4 is connected by welding at one location in the circumferential direction. The series of processing steps for the cage 2 is as follows. A strip-shaped plate material Bm shown in FIG. 4(a) is bent into a concave cross-sectional shape, i.e., a gate shape, to form a pair of annular portions 4, 4 (FIG. 4(b)). Next, as shown in FIG. 4(c), the portions of each annular portion 4 other than the retaining claws 6 are punched, and after a pocket punching process (not shown) is performed, the retaining claws 6 are bent as shown in FIG. 4(d).

[0037] Next, as shown in Figure 4(e), a portion of the plate material Bm in the longitudinal direction is cut to a predetermined size. Thereafter, as shown in Figure 4(f), each annular portion 4 is bent into an annular shape so that the retaining claws 6 are positioned on the inner diameter side, and one location in the circumferential direction of each annular portion 4 is joined by welding. This one location in the circumferential direction of the annular portions 4 joined by welding is designated as a welded portion We. Thereafter, the entire cage 2 is subjected to heat treatment, etc., as described below.

[0038] <Regarding non-edged retention claws> As shown in Fig. 6, the contact portions Cp of the retention claws 6 with the rollers 3 are made non-edged to prevent wear and scratches. In order to make the contact portions Cp of the retention claws 6 non-edged, as shown in Fig. 5A, both ends of the plate material Bm in the short direction are bent into a concave cross-section and then punched. In other words, a portion of each annular portion 4 is punched by a press from the axial center of the cage toward both axial sides (directions C1 toward the width faces of the cage).

[0039] During the punching process using the press, a sag Dr, shown by the shaded area in Fig. 5A, occurs on the axial center side of the holding jaw 6. As shown in Fig. 5B, the sag Dr remains even after bending the holding jaw 6, so the outer diameter side corners of the holding jaw 6 can be made non-edged. The "sag" refers to a shrinkage of the material caused by pressing a tool such as a punch into the material, and in this example refers to the rounded R-shaped portion 6c on the surface of the plate material shown in Fig. 7.

[0040] The inner diameter side corners 6d of the retaining claws 6 also become contact areas when the rollers are pressed in, so edges are undesirable. For this reason, the edges of the inner diameter side corners 6d are removed by barrel processing or the like in the latter half of the processing process. Since the outer diameter side corners of the retaining claws 6 are difficult to remove by barrel processing, it is preferable to make them non-edged by the above-described press sag Dr (FIG. 5A) in order to shorten the processing time.

[0041] <Regarding the angle of the retention claws> As shown in Figures 8A and 8B, the angle α of the retention claws 6 with respect to the width surface 2w of the cage 2 is between 70° and 90°. When the rollers 3 shown in Figure 2 are press-fitted from the inner diameter side of the cage 2, the rollers 3 are more easily press-fitted with a stable posture if the retention claws 6 and the central axis of the rollers 3 are parallel. Furthermore, the inner diameter of the annular portion 4 bent toward the inner diameter is preferably as small as possible to increase the ring rigidity of the cage 2, and it is advantageous to bend the retention claws 6 to an extent that they are parallel to the central axes of the rollers 3. In terms of actual management, it is easier to express the retention claws 6 in terms of the angle α with respect to the width surface 2w of the cage 2, as shown in Figure 8A, so for the two reasons mentioned above, it is preferable that the angle α of the retention claws 6 with respect to the width surface 2w of the cage 2 be 90°.

[0042] Considering springback, bending the retention claws 6 to 90° requires pressing from the inner diameter side toward the radially outward direction. This requires a complex die structure, which is disadvantageous in terms of cost, so the retention claws 6 may be bent in the axial direction. For example, it is more economical to use a cylindrical die to bend all of the roller retention claws 6 around the circumference from the axial direction at once. As described above, considering springback of the retention claws 6, it is practical to set the angle α of the retention claws 6 with respect to the width surface 2w of the cage 2 to be between 70° and 90°, as shown in Figures 8A and 8B.

[0043] 9, tip end 6e of retention pawl 6 is located axially inward from roller end face 3b by 2.5 × axial chamfer dimension of roller 3 to 0.25 × roller length. In other words, with roller end face 3b as the reference, tip end position P6 of retention pawl 6 is located axially inward by 2.5 or more times the axial chamfer dimension of roller 3 and 25% or less of the roller length.

[0044] The rollers 3 have chamfered portions 3a, and are press-fit into the cage 2 within the contact area between the retaining pawls 6 and the chamfered portions 3a, and this contact range is also where the rollers are prevented from falling off. Therefore, it is sufficient for the tip position P6 of the retaining pawls 6 to be the intersection of the roller chamfer and the roller outer diameter surface. In practice, it is preferable to position the contact position between the rollers 3 and the retaining pawls 6 near the axial center of the chamfered portions 3a of the rollers 3, taking into account variations in each part, and the tip position P6 of the retaining pawls 6 near the axial center of the chamfered portions 3a will still function satisfactorily.

[0045] As mentioned above, because the rollers 3 and the retention claws 6 come into contact, making the length of the retention claws 6 longer than necessary will increase material costs and reduce oil permeability. Therefore, considering the amount of axial movement of the rollers 3 within the cage, it is sufficient for the retention claw tips to be located at a position 2.5 times the axial chamfer dimension of the rollers 3. However, it is anticipated that bending the retention claws 6 may be difficult due to the short length of the claw portions. In cases where the roller length is relatively long, it may be better to prioritize workability rather than insisting on a position 2.5 times the axial chamfer dimension of the rollers 3. In such cases, it is preferable to set the retention claw tip position P6 at a position approximately 25% of the roller length to avoid a significant reduction in oil permeability.

[0046] 10 and 11, the radial position of the retention claws 6 satisfies both of the following formulas (1) (see FIG. 10) and (2) (see FIG. 11): (roller circumscribing circle diameter Cd - cage outer diameter 2D) / 2 < radial clearance δ1 between rollers 3 and roller retention claws 6 ...formula (1) (roller circumscribing circle diameter Cd - cage outer diameter 2D) / 2 < cage inner diameter 2d - roller inscribing circle diameter Ce ...formula (2) If the retention claws 6 of the cage 2 come into contact with the shaft Sh, it will hinder the drive of the cage 2, so it is desirable that the retention claws 6 do not come into contact with the shaft Sh. The retention claws 6 serve only to prevent the rollers 3 from falling off, and if the rollers 3 and retention claws 6 come into contact with each other during operation, the lubricant on the roller surface will be scraped off, and a load will be applied to the retention claws 6, so consideration must be given to the strength of the retention claws 6.

[0047] It is preferable to set the retention pawls 6 so that they do not come into contact with the shaft Sh and so that they do not come into contact with the rollers 3 during operation. However, if the rollers 3 are not in contact with the retention pawls 6 at all during operation, the thickness of the retention pawls themselves may become too small, increasing the risk of the rollers falling off. One of the conditions under which the load received by the retention pawls 6 from the rollers 3 becomes large is when the roller 3 simultaneously comes into contact with the retention pawls 6, 6 on the front and rear sides in the direction of rotation C2 of one roller 3, and a wedge effect is also added, causing the retention pawls 6, 6 to spread apart with a large force.

[0048] In particular, the wedge effect is likely to be relatively large because the distance between the retaining claws 6, 6 is set so that the rollers 3 can be press-fit from the inner diameter portion of the cage 2. In order to prevent the rollers 3 from contacting the front and rear retaining claws 6, 6 simultaneously, it is preferable that the radial positions of the retaining claws 6 satisfy all of the relationships in equations (1) and (2) above. Note that although equations (1) and (2) are shown as relational expressions determined from the roller circumscribing circle diameter Cd and the roller inscribing circle diameter Ce, they may also be relational expressions calculated from the raceway diameters for the roller circumscribing side and the roller inscribing side, respectively.

[0049] <Cross-Sections of the Retention Claws, etc.> As shown in Figure 10 , the cross-section of the retention claws 6 cut along an imaginary plane perpendicular to the axial direction is rectangular. When the cage 2 is manufactured by welding, both ends of the shorter side of a strip-shaped plate material are bent toward the inner diameter. If it is assumed that the pocket Pt is then punched and the portions of each annular portion 4 ( Figure 9 ) other than the retention claws 6 are press-punched, the column portions 5 on the outer diameter side and the retention claws 6 will each be roughly rectangular in a cross-section of the completed cage cut along an imaginary plane perpendicular to the axial direction. In this case, when the rollers 3 are press-fitted from the inner diameter portion of the cage 2, the largest press-fit amount occurs on the inner diameter side of the retention claws, which can reduce plastic deformation of the outer diameter portion of the retention claws that affects the radial clearance δ1 between the rollers 2 and the retention claws 6 as shown in Figures 10 and 11 .

[0050] <Radial dimension of straight portion of width face> As shown in Figure 12, the radial dimension Sd of the straight portion of the width face 2w of the cage 2 is equal to or greater than 0.4 times the roller diameter. When two or more roller bearings 1 are used in a double row so that they are adjacent in the axial direction, if a radial load is applied during rotation, a load known as induced thrust will be generated in the axial direction due to factors such as shaft deflection or shape error of the raceway surface. This load will be borne by the cage width faces that are adjacent in the axial direction.

[0051] For this reason, in order to reduce the surface pressure, it is preferable to make the area of ​​the width surface 2w of the cage 2 as large as possible. Depending on the application, the central axes of the raceway surfaces of axially adjacent roller bearings 1 may be eccentric with respect to the axis AX, which is the central axis of rotation, and the eccentric directions may differ, which may further reduce the contact area of ​​the width surface 2w of the cage 2.

[0052] In this embodiment, as described above in the section <Regarding the Angle of the Retention Claws>, the inner diameter of the annular portion 4 can be reduced when both ends of the shorter sides of the plate material are bent inward. This makes it possible to increase the range of the width surface 2w of the cage 2. The range of the width surface 2w of the cage 2 is calculated by (cage outer diameter 2D - annular portion inner diameter 4d) / 2 - the radial chamfer dimension of the annular portion 4. However, because the radial chamfer dimension is a press process, it cannot be arbitrarily reduced as in cutting processes, and considering the bending workability of the retention claws 6, the inner diameter of the annular portion 4 bent inward is also limited.

[0053] From these, the radial straight length of the width surface 2w relative to the roller diameter is roughly equal to 0.4 times the roller diameter. However, a large straight portion of the width surface 2w means a large difference between the cage outer diameter 2D and the annular portion inner diameter 4d, making it difficult to cut the sheet material into a ring. For this reason, the current limit for machining the straight portion of the width surface 2w is about 5 mm.

[0054] <Material> The material of the cage 2 is selected from cold-rolled steels such as SPC specified in JIS G 3141 conforming to ISO 3574, low-carbon steels such as S15C specified in JIS G 4051 conforming to ISO C15E4 and ISO C15M2, and case-hardened steels such as SCM specified in JIS G 4052 conforming to ISO 18CrMo4, ISO 18CrMoS4, ISO 34CrMo4, ISO 34CrMoS4, ISO 42CrMo4, and ISO 42CrMoS4. The carbon content of the cage 2 is preferably 0.08% by mass or more and 0.20% by mass or less. A carbon content within this range ensures good hardenability and weldability for the cage 2.

[0055] As mentioned above, in some applications of roller bearings 1, roller bearings 1 are arranged adjacent to each other in the axial direction, generating induced thrust forces during operation. Therefore, sliding friction occurs as the roller bearings 1 rotate while rubbing against the width surfaces 2w, making it essential to ensure surface hardness against wear. Furthermore, toughness is also required to withstand the stresses generated when the rollers are press-fitted and when the roller retaining claws are bent. To satisfy these conditions, the cage 2 is preferably made of a material that can be carburized. In other words, the cage 2 preferably has a carbon content of 0.08 to 0.20 mass % and has been subjected to carburized heat treatment.

[0056] <Surface Treatment> The welded portion We shown in FIG. 4( f) may have lower corrosion resistance than non-welded portions. For this reason, it is effective to apply a surface treatment with an anti-rust effect to the cage 2. The surface treatment also improves the sliding properties of the cage guide surfaces, etc. For this reason, the cage 2 may be plated or subjected to a relatively inexpensive black oxide treatment. Examples of the plating include nickel, copper, silver, and gold.

[0057] <Surface Roughness> The surface roughness of the cage 2 shown in FIG. 12 is preferably an arithmetic mean roughness Ra of 1.0 μm or less. The definition of arithmetic mean roughness Ra conforms to JIS B 0601 (ISO 25178). In addition to uneven stresses occurring when a load is applied due to the shape of the cage 2, unevenness in each part caused by press working and welding is expected. For this reason, it is preferable to devise a way to reduce the load itself applied to the cage 2.

[0058] One method for reducing the load is to reduce the contact resistance of each part (reduction of frictional force), and it is desirable to maintain a certain level of roughness in order to improve the oil film formation ability at the contact parts of the outer diameter side guide surface Of and the width surface 2w of the cage 2. When used as a cage 2, an arithmetic mean roughness Ra of 1.0 μm or less will enable good oil film formation and also reduce contact wear with the mating member.

[0059] <Roller Occupancy Rate on P.C.D.> As shown in Figures 10 and 11, the roller bearing 1 requires sufficient space between the rollers 3, 3 so that the retaining pawls 6, 6 on the front and rear of the direction of rotation C2 do not come into contact with the rollers 3 simultaneously during operation (satisfying the above formulas (1) and (2)). Although it depends on the roller diameter and cage thickness, the occupancy rate of the rollers 3 on the pitch circle diameter PCD should be approximately 90% or less. This occupancy rate is expressed as follows: Occupancy Rate = {(d x n) / (PCD x π)} x 100 where d: roller diameter, n: number of rollers, PCD: pitch circle diameter of the roller arrangement

[0060] <Roller chamfer dimension> As shown in Figure 12, this roller bearing 1 is held by the retaining pawls 6 at the roller chamfer 3a, and is shaped so that the rollers 3 do not fall off to the inner diameter side. For this reason, the larger the chamfer 3a of the roller 3, the greater the degree of freedom in setting the axial length of the retaining pawls 6. However, since increasing the chamfer 3a of the roller 3 reduces the load capacity of the bearing 1, it is desirable that the axial chamfer dimension 3aa of the roller 3 satisfy the following condition: 2.5% of roller diameter≦axial chamfer dimension of roller 3≦30% of roller diameter

[0061] <Thickness of the Retention Claws> As shown in Figure 13, the thickness of the column portions 5 of the cage 2, i.e., the radial thickness, is preferably as thick as possible to provide strength against induced thrust forces. However, the retention claws 6 exist only to hold the rollers 3, and the contact between the rollers 3 and the retention claws 6 during operation is designed to satisfy the above-mentioned formulas (1) and (2) so that a large load is not applied. As a result, it is not necessarily necessary to increase the thickness t6, which is the radial thickness of the retention claws 6. However, without a certain thickness t6, it becomes difficult to ensure precision due to deformation during processing, and as a result, processing the retention claws 6 becomes difficult.

[0062] For this reason, the plate thickness t6 of the retention claw 6 needs to be at least about 10% of the roller diameter DSA. If the plate thickness t6 of the retention claw 6 is too thick, as mentioned above, there is an increased risk that the retention claws 6, 6 on the front and rear sides in the direction of rotation C2 will simultaneously come into contact with the rollers 3 during operation. For this reason, it is desirable to keep the plate thickness t6 of the retention claw 6 to about 30% of the roller diameter DSA.

[0063] <Shape of Retention Pawl> In the roller bearing 1 according to this embodiment, the rollers 3 are press-fitted into the retention pawls 6 within the chamfered portions of the rollers 3, preventing the rollers 3 from falling out towards the inner diameter side. If the root portions 6a and tip portions 6b of the retention pawls 6 have the same width (circumferential width), as in Figure 14A , the total amount of elastic deformation during press-fitting becomes large, raising concerns about plastic deformation of the retention pawls 6. For this reason, as in Figure 14B , the retention pawls 6 are tapered so that the tip portion width 6ba is smaller than the root portion width 6aa.

[0064] 15, an example of a tapered shape is one in which, at the maximum interference position where the interference IF between the retaining claws 6 and rollers 3 is at its maximum, the maximum interference IFmax is 2% to 6% of the roller diameter. This is because, normally, if the pocket of a cage is approximately 98% of the roller diameter, the rollers 3 are easily assembled and do not fall out, but in this embodiment, the welded cage does not have good precision and is cantilevered, so an overlapping allowance is necessary compared to conventional cages.

[0065] <Operation and Effect> According to the roller bearing 1 of Figure 1 described above, the number of parts can be kept to a minimum, namely the rollers 3 and the cage 2, making it possible to obtain a high load capacity in a limited space. As shown in Figure 4(f), one point in the circumferential direction of each annular portion 4 of the cage 2 is joined by welding. Therefore, after the cage is completed after bending the retaining claws 6, heat treatment can be performed on the retaining claws 6, eliminating the need for special treatment such as carburization prevention treatment on the retaining claws 6.

[0066] Furthermore, because each annular portion 4 is connected by welding at one point in the circumferential direction, when the retaining claws 6 are in the completed state of the cage after bending or other processes have been performed on the retaining claws 6, the rollers 3 are inserted by elastic deformation of the retaining claws 6 by press-fitting from the inner diameter side of the retaining claws 6, as shown in Figure 2. This makes it relatively easy to assemble the roller bearing 1 compared to the conventional technique in which the retaining claws 6 are bent after the rollers have been inserted, and by eliminating the need for the aforementioned guide jig or the like, there are no restrictions on the inner diameter dimension of the annular portion 4, allowing for greater freedom of design.

[0067] The retaining claws 6 are bent piece-shaped roller retaining claws provided in the inner diameter portion of the annular portion 4 in the portion between adjacent rollers 3, 3. Therefore, by minimizing the axial length of the retaining claws 6, it is possible to ensure a wider exposed portion of the rollers on the inner diameter side than in the prior art, thereby improving oil permeability.

[0068] As shown in Figure 9, the tip end 6e of the retaining claw 6 is positioned axially inward from the roller end face 3b by 2.5 x the axial chamfer dimension of the roller to 0.25 x the roller length. In this case, it is possible to prevent the rollers 3 from falling off, improve the workability of the retaining claw 6, and prevent a decrease in oil permeability. As shown in Figures 10 and 11, by satisfying both of the above formulas (1) and (2), it is possible to prevent excessive contact between the rollers 3 and the retaining claws 6 without interfering with the drive of the cage 2.

[0069] As shown in Figure 12, when the axial chamfer dimension 3aa of the roller 3 is set to 2.5% to 30% of the roller diameter, the degree of freedom in setting the axial length of the retention claws 6 can be increased and the load capacity can be improved. As shown in Figure 14B, the retention claws 6 are tapered so that the tip width 6ba is smaller than the base width 6aa. In this case, plastic deformation of the retention claws 6 during roller press-fitting can be prevented, and the rollers 3 can be prevented from falling off toward the inner diameter side. As shown in Figure 12, the cage 2 is plated or blackened. In this case, a decrease in corrosion resistance of the welded portion We (Figure 1) can be prevented, and the sliding performance of the cage guide surfaces, etc. can be improved.

[0070] <Regarding Other Embodiments> In the following description, parts corresponding to matters previously described in each embodiment are assigned the same reference numerals, and duplicated description will be omitted. When only part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also parts of the embodiments together, provided that there is no particular problem with the combination.

[0071] 16B or 16C , a roller bearing may be provided with a cage 2 including an inclined surface 5a that slopes so that the column width (circumferential width of the column 5) decreases radially inward in a cross section of the column 5 cut along an imaginary plane perpendicular to the axial direction. When the packing density of the rollers 3 is increased, as in the conventional cage shown in Fig. 16A , the space between the rollers 3 decreases. As this space decreases, the column width also decreases, but the outer diameter side of the column 5 needs to have strength against induced thrust forces.

[0072] As a measure to ensure the cross-sectional area and strength of the column portion 5 even in a limited space, the cross section of the column portion 5 may be tapered, including an inclined surface 5a, as shown in Figure 16B. Alternatively, the cross section of the column portion 5 may be trapezoidal, including an inclined surface 5a, as shown in Figure 16C. In these cases, as shown in Figure 16B, the cage pocket width is characterized in that the pocket width A on the outer diameter side is smaller than the pocket width B on the inner diameter side. The cross-sectional shape of the column portion shown in Figure 16B or 16C makes it possible to ensure the cross-sectional area and strength of the column portion 5 in a limited space.

[0073] 17 , the roller bearing 1A may include both the inner and outer rings 13 and 14. The roller bearing 1A may also include only one of the inner and outer rings 13 and 14. The cage of the first or second embodiment described above can be applied to such various roller bearings.

[0074] As described above, the preferred embodiment has been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included in the scope of the present invention.

[0075] DESCRIPTION OF SYMBOLS 1, 1A... roller bearing 2... cage 3... roller 4... annular portion 5... column portion 6... roller retaining claw 6a... root portion 6b... tip portion 13... inner ring 14... outer ring We... welded portion

Claims

1. A roller bearing comprising a plurality of rollers and a cage that holds these rollers, the cage having a pair of annular portions facing both axial ends of each of the rollers, and a plurality of pillar portions that are installed across the outer diameter portions of the pair of annular portions and are provided at regular intervals in the circumferential direction, the cage having a welded portion where each of the annular portions is connected by welding at one point in the circumferential direction, and wherein the inner diameter portion of each of the annular portions is provided with a roller retaining claw that prevents the rollers from slipping out towards the inner diameter side of the cage.

2. A roller bearing according to claim 1, comprising either an inner ring or an outer ring, or both.

3. A roller bearing according to claim 1 or 2, wherein the roller retaining pawls are bent piece-shaped roller retaining pawls provided in the area between adjacent rollers on the inner diameter part of the annular part.

4. A roller bearing according to claim 3, wherein the angle of the roller retaining claws relative to the width face of the cage is between 70° and 90°.

5. A roller bearing as set forth in claim 3, wherein the tip end of the roller retaining pawl is positioned axially inward from the roller end face by an amount ranging from 2.5 x the axial chamfer dimension of the roller to 0.25 x the roller length.

6. A roller bearing as set forth in claim 3, wherein the radial position of the roller retaining claws satisfies the following formula: (roller circumscribing diameter - cage outer diameter) / 2 < radial clearance between roller and roller retaining claws (roller circumscribing diameter - cage outer diameter) / 2 < cage inner diameter - roller inscribing diameter 7. A roller bearing according to claim 3, wherein the roller retaining pawl has a rectangular cross section when cut along an imaginary plane perpendicular to the axial direction.

8. A roller bearing according to claim 3, wherein the width of the tip end of each of the roller retaining pawls is smaller than the width of the base end.

9. A roller bearing according to claim 1 or 2, wherein the axial chamfer dimension of the rollers is 2.5% to 30% of the roller diameter.

10. A roller bearing according to claim 1 or 2, wherein the cage has a carbon content of 0.08 to 0.20 mass % and has been subjected to carburizing heat treatment.

11. A roller bearing according to claim 1 or 2, wherein the cage is plated or blackened.

12. A roller bearing as claimed in claim 1 or claim 2, wherein the cross section of the column portion cut along an imaginary plane perpendicular to the axial direction includes an inclined surface that slopes so that the column portion width decreases radially inward.

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