Raceway rings and tapered roller bearings

Abstract

To provide a bearing ring capable of improving roundness on a raceway surface.SOLUTION: A bearing ring comprises an inner diameter surface and an outer diameter surface extending in a circumferential direction, which is a direction along a circumference centered on a central axis of the bearing ring. One of the inner diameter surface and the outer diameter surface has a raceway surface. A value obtained by dividing an outer diameter of the bearing ring by an inner diameter of the bearing ring is 1.1 or less. A value obtained by dividing a maximum thickness of the bearing ring in an axial direction, which is a direction along the central axis, by a minimum thickness of the bearing ring in the axial direction is 2.0 or more. The difference between a maximum value of a diameter of the raceway surface and a minimum value of the diameter of the raceway surface is more than 1 time and 2 times or less an upper limit of JIS 0 class. An amount of uneven thickness of the bearing ring is not more than 2×10-4 times the outer diameter of the bearing ring.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an orbital ring and a tapered roller bearing.

Background Art

[0002] For example, Japanese Patent No. 6778310 (Patent Document 1) describes an outer ring of a tapered roller bearing. The direction along the central axis of the outer ring described in Patent Document 1 is defined as the axial direction. The direction orthogonal to the axial direction and passing through the central axis of the outer ring described in Patent Document 1 is defined as the radial direction. The direction along the circumference centered on the central axis of the outer ring described in Patent Document 1 is defined as the circumferential direction. The outer ring described in Patent Document 1 has a first end face, a second end face, an inner diameter face, and an outer diameter face.

[0003] The first end face and the second end face are end faces in the axial direction. The inner diameter face and the outer diameter face extend in the circumferential direction. The inner diameter face faces the central axis side. The outer diameter face faces the side opposite to the central axis. The inner diameter face has a raceway surface. The raceway surface is a portion of the inner diameter face that contacts the tapered roller. The raceway surface extends in the circumferential direction. The diameter of the raceway surface increases from the first end face side toward the second end face side. The angle (contact angle) formed between the raceway surface and the central axis is 40° or more and 50° or less. A flange portion that protrudes inward in the radial direction is formed in a portion of the inner diameter face between the raceway surface and the second end face.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the outer ring described in Patent Document 1, the difference between the maximum and minimum wall thickness in the axial direction is large. Therefore, in the outer ring described in Patent Document 1, when the value obtained by dividing the outer diameter by the inner diameter is small (i.e., the wall thickness in the radial direction is small), the roundness of the raceway surface may be low due to heat treatment or machining.

[0006] This invention has been made in view of the problems of the prior art described above. More specifically, this invention provides a raceway ring and a tapered roller bearing that can improve the roundness of the raceway surface. [Means for solving the problem]

[0007] The raceway of the present invention comprises an inner diameter surface and an outer diameter surface extending in the circumferential direction, which is along the circumference of a circle centered on the central axis of the raceway. One of the inner diameter surface and the outer diameter surface has a raceway surface. The value obtained by dividing the outer diameter of the raceway by the inner diameter of the raceway is 1.1 or less. The value obtained by dividing the maximum wall thickness of the raceway in the axial direction, which is along the central axis, by the minimum wall thickness of the raceway in the axial direction is 2.0 or more. The difference between the maximum diameter and the minimum diameter of the raceway surface is more than 1 and 2 times or less the upper limit of JIS Class 0. The thickness variation of the raceway is 2 × 10⁻⁶ of the outer diameter of the raceway. -4 It is less than double.

[0008] In the above-described raceway, the value obtained by dividing the maximum thickness of the raceway in the axial direction by the minimum thickness of the raceway in the axial direction may be 3.0 or greater.

[0009] The above-mentioned raceway ring may be the outer ring of a tapered roller bearing. The inner diameter surface may have a raceway surface. The angle between the raceway surface and the axial direction may be between 35° and 55°.

[0010] The raceway ring described above may further comprise a first end face and a second end face, which are end faces in the axial direction. The distance between the raceway surface and the outer diameter surface in the radial direction perpendicular to the axial direction may decrease from the first end face side toward the second end face side. A flange portion projecting radially inward may be formed on the inner diameter surface portion between the raceway surface and the second end face. The raceway ring described above may be formed from hardened and tempered steel.

[0011] The tapered roller bearing of the present invention comprises an outer ring and tapered rollers. The outer ring has an inner diameter surface and an outer diameter surface extending in the circumferential direction, which is along the circumference of a circle centered on the central axis of the outer ring, and a first end surface and a second end surface which are end surfaces in the axial direction, which is along the central axis. The inner diameter surface includes the raceway surface. The value obtained by dividing the outer diameter of the outer ring by the inner diameter of the outer ring is 1.1 or less. The value obtained by dividing the maximum wall thickness of the outer ring in the axial direction by the minimum wall thickness of the outer ring in the axial direction is 2.0 or more. The difference between the maximum diameter and the minimum diameter of the raceway surface is more than 1 and 2 times or less the upper limit of JIS Class 0. The thickness variation of the outer ring is 2 × 10⁻⁶ of the outer diameter of the outer ring. -4 It is less than double. The angle between the raceway surface and the axial direction is between 35° and 55°. The distance between the raceway surface and the outer diameter surface in the radial direction perpendicular to the axial direction decreases from the first end face side to the second end face side. A flange portion is formed on the inner diameter surface between the raceway surface and the second end face, projecting inward in the radial direction.

[0012] The above-described tapered roller bearing may further include an inner ring. The value obtained by dividing the outer diameter of the outer ring by the inner diameter of the inner ring may be 1.3 or less. [Effects of the Invention]

[0013] According to the raceway ring and tapered roller bearing of the present invention, it is possible to improve the roundness of the raceway surface. [Brief explanation of the drawing]

[0014] [Figure 1] This is a cross-sectional view of the outer ring 10. [Figure 2]It is a cross-sectional view of a rolling bearing 100 having an outer ring 10. [Figure 3] It is a process drawing showing a method for manufacturing the outer ring 10.

Embodiments for Carrying out the Invention

[0015] Details of the embodiments of the present invention will be described while referring to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will not be repeated.

[0016] The raceway ring according to the embodiment is, for example, the outer ring 10 of a tapered roller bearing. The raceway ring according to the embodiment is not limited to the outer ring 10, but in the following, the outer ring 10 will be described as an example of the raceway ring according to the embodiment.

[0017] (Configuration of the outer ring 10) The configuration of the outer ring 10 will be described below.

[0018] FIG. 1 is a cross-sectional view of the outer ring 10. In FIG. 1, a cross-section of the outer ring 10 that is parallel to the central axis A of the outer ring 10 and passes through the central axis A is shown. The direction along the central axis A is defined as the axial direction. The direction that is orthogonal to the axial direction and passes through the central axis A is defined as the radial direction. The direction along the circumference centered on the central axis A is defined as the circumferential direction. As shown in FIG. 1, the outer ring 10 has a first end face 10a, a second end face 10b, an inner diameter face 10c, and an outer diameter face 10d.

[0019] The first end face 10a and the second end face 10b are end faces of the outer ring 10 in the axial direction. The second end face 10b is the opposite face of the first end face 10a in the axial direction. The inner diameter face 10c extends in the circumferential direction. The inner diameter face 10c faces the central axis A side.

[0020] The inner diameter surface 10c has a raceway surface 10ca. The raceway surface 10ca is the portion of the inner diameter surface 10c that contacts rolling elements (the tapered roller 30 described later) not shown in the figure. The inner diameter surface 10c extends in the circumferential direction. The inner diameter surface 10c is parallel to the central axis A and is inclined with respect to the axial direction in a cross-sectional view passing through the central axis A. More specifically, the raceway surface 10ca is inclined such that the distance between it and the outer diameter surface 10d in the radial direction decreases from the first end face 10a side toward the second end face 10b side.

[0021] The contact angle θ is the angle formed by the raceway surface 10ca and the central axis A. The contact angle θ is preferably 35° or more and 55° or less. From another perspective, the raceway surface 10ca has a steep gradient. A flange portion 10e is formed in the portion of the inner diameter surface 10c between the raceway surface 10ca and the second end face 10b. The flange portion 10e protrudes inward in the radial direction.

[0022] The outer diameter surface 10d extends in the circumferential direction. The outer diameter surface 10d faces the side opposite to the central axis A. From another perspective, the outer diameter surface 10d is the opposite surface of the inner diameter surface 10c in the radial direction. The outer ring 10 is fitted into a housing not shown at the outer diameter surface 10d.

[0023] The outer ring 10 is formed of steel that has been quenched and tempered. The outer ring 10 is formed of, for example, high-carbon chromium bearing steel defined by the JIS standard that has been quenched and tempered. However, the constituent material of the outer ring 10 is not limited to this.

[0024] Let the inner diameter of the outer ring 10 be the inner diameter D1. The inner diameter D1 is the distance between two portions of the inner diameter surface 10c that face each other across the central axis A in the radial direction. The inner diameter D1 is measured at the position where the distance between two portions of the inner diameter surface 10c that face each other across the central axis A in the radial direction is minimized.

[0025] The outer diameter of the outer ring 10 is denoted as outer diameter D2. Outer diameter D2 is the distance between two parts of the outer diameter surface 10d that are opposite each other with respect to the central axis A in the radial direction. Outer diameter D2 is measured at the position where the distance between the two parts of the outer diameter surface 10d that are opposite each other with respect to the central axis A in the radial direction is maximum. The value obtained by dividing outer diameter D2 by inner diameter D1 is 1.1 or less. The value obtained by dividing outer diameter D2 by inner diameter D1 is greater than 1.0. Note that the value obtained by subtracting inner diameter D1 from outer diameter D2 and then dividing by 2 is, for example, 8 mm or more and 18 mm or less.

[0026] Let the thickness of the outer ring 10 be denoted as thickness T. Thickness T is the distance between the inner diameter surface 10c and the outer diameter surface 10d in the radial direction. Note that thickness T changes with position in the axial direction. More specifically, thickness T decreases from the first end surface 10a side to the second end surface 10b side, and then increases again. The value obtained by dividing the maximum value of thickness T in the axial direction by the minimum value of thickness T in the axial direction is 2.0 or greater. Preferably, the value obtained by dividing the maximum value of thickness T in the axial direction by the minimum value of thickness T in the axial direction is 3.0 or greater.

[0027] The thickness variation of the outer ring 10 is 2 × 10 of the outer diameter D2. -4 It is less than double. The thickness variation of the outer ring 10 is the difference between the maximum and minimum values ​​when the wall thickness T is measured along the circumferential direction. The thickness variation of the outer ring 10 is calculated based on the maximum and minimum values ​​when the wall thickness T is measured along the circumferential direction. The thickness variation of the outer ring 10 is measured at the axial position where the wall thickness T is minimum.

[0028] Let D3 be the diameter of the raceway surface 10ca. D3 is the distance between two parts of the raceway surface 10ca that are opposite each other with respect to the central axis A in the radial direction. D3 is measured at the center of the raceway surface 10ca in the axial direction. The difference between the maximum and minimum values ​​of D3 (i.e., the roundness of the raceway surface 10ca) is greater than 1 times the upper limit of JIS Class 0. The roundness of the raceway surface 10ca is less than or equal to 2 times the upper limit of JIS Class 0. Note that the upper limit of JIS Class 0 is 1 × 10⁻⁶ of the outer diameter of the raceway ring when the raceway surface is formed on the inner diameter surface (i.e., the raceway ring is an outer ring). -4 It is twice as large, and when the raceway is formed on the outer diameter surface (i.e., when the raceway is an inner ring), it is 1 × 10 times the inner diameter of the raceway. -4 It is double.

[0029] Let the inner diameter of the outer ring 10 at the flange portion 10e be the inner diameter D4. The value obtained by dividing the outer diameter D2 by the inner diameter D4 is, for example, 1.05 or less.

[0030] Figure 2 is a cross-sectional view of a rolling bearing 100 having an outer ring 10. Figure 2 shows a cross-section of the rolling bearing 100 that is parallel to and passes through the central axis A. As shown in Figure 2, in addition to the outer ring 10, the rolling bearing 100 has an inner ring 20, a plurality of tapered rollers 30, and a cage 40. The rolling bearing 100 is a tapered roller bearing used, for example, in a reduction gear for robots or construction machinery.

[0031] The inner ring 20 has a first end face 20a, a second end face 20b, an inner diameter face 20c, and an outer diameter face 20d. The first end face 20a and the second end face 20b are the end faces of the inner ring 20 in the axial direction. The second end face 20b is the opposite face of the first end face 20a in the axial direction.

[0032] The inner diameter surface 20c extends in the circumferential direction. The inner diameter surface 20c faces the central axis A. The inner ring 20 is fitted onto an axis (not shown) at the inner diameter surface 20c. The outer diameter surface 20d extends in the circumferential direction. The outer diameter surface 20d faces away from the central axis A (i.e., it is the opposite surface of the inner diameter surface 20c in the radial direction).

[0033] The outer diameter surface 20d has a raceway surface 20da. The raceway surface 20da is the portion of the outer diameter surface 20d that contacts the tapered roller 30. The raceway surface 20da is oriented circumferentially. The raceway surface 20da is inclined axially such that the distance between it and the inner diameter surface 20c in the radial direction increases from the first end face 20a side to the second end face 20b side. The inner ring 20 is positioned radially inside the outer ring 10 such that the raceway surface 20da faces the raceway surface 10ca. Note that no flange is formed on the outer diameter surface 20d.

[0034] Let the inner diameter of the inner ring 20 be defined as inner diameter D5. Inner diameter D5 is the distance between two parts of the inner diameter surface 20c that are opposite each other with respect to the central axis A in the radial direction. Inner diameter D5 is measured at the position where the distance between the two parts of the inner diameter surface 20c that are opposite each other with respect to the central axis A in the radial direction is minimized. The value obtained by dividing the outer diameter D2 by the inner diameter D5 is, for example, 1.3 or less. The value obtained by subtracting the inner diameter D5 from the outer diameter D2 and then dividing by 2 is, for example, 20 mm or more and 35 mm or less.

[0035] Multiple tapered rollers 30 are arranged circumferentially between raceway surfaces 10ca and 20da. The outer surfaces of the tapered rollers 30 are in contact with raceway surfaces 10ca and 20da. Each tapered roller 30 has a large-diameter end face and a small-diameter end face in the direction along its central axis. The large-diameter end face of each tapered roller 30 is in contact with the flange portion 10e. The retainer 40 holds the multiple tapered rollers 30 such that the distance between two adjacent tapered rollers 30 in the circumferential direction is within a certain range.

[0036] (Manufacturing method for the outer ring 10) The manufacturing method for the outer ring 10 is described below.

[0037] Figure 3 is a process diagram showing the manufacturing method of the outer ring 10. As shown in Figure 3, the manufacturing method of the outer ring 10 includes a preparation step S1, a quenching step S2, a tempering step S3, and a machining step S4.

[0038] In preparation step S1, the workpiece to be processed is prepared. The workpiece to be processed is made of the same steel as the outer ring 10. The workpiece to be processed is an annular member. The quenching step S2 is performed after preparation step S1. In quenching step S2, the workpiece to be processed is quenched. More specifically, in quenching step S2, the workpiece to be processed is heated to a temperature above the A1 transformation point of the steel constituting the workpiece, and then the M S This is done by cooling the temperature to below the transformation point.

[0039] The tempering process S3 is performed after the quenching process S2. In the tempering process S3, tempering is performed on the workpiece. More specifically, the tempering process S3 is performed by holding the workpiece at a temperature below the A1 transformation point of the steel constituting the workpiece, and then allowing it to cool. When attempting to manufacture an outer ring 10 such that the value obtained by dividing the outer diameter D2 by the inner diameter D1 is 1.3 or less, the shape of the workpiece may be distorted due to the thermal history during the quenching process S2 and the tempering process S3. Note that the heat treatment performed on the workpiece is not limited to the quenching process S2 and the tempering process S3.

[0040] The machining process S4 is performed after the tempering process S3. In the machining process S4, the workpiece is chucking, and then machining (e.g., grinding, polishing, etc.) is performed on the surface of the workpiece. Through this process, the outer ring 10 with the structure shown in Figure 1 is manufactured. When the machining is completed and the outer ring 10 is released from the chucking, the roundness of the raceway surface 10ca may be compromised.

[0041] (Effect of outer ring 10) The effect of the outer ring 10 is explained below.

[0042] As described above, in the outer ring 10, the value obtained by dividing the outer diameter D2 by the inner diameter D1 is 1.1 or less. In other words, the wall thickness T of the outer ring 10 is small. In addition, in the outer ring 10, a flange portion 10e is formed on the inner diameter surface 10c, and the raceway surface 10ca is steeply sloped (the contact angle θ is between 35° and 55°). As a result, in the outer ring 10, the difference between the maximum and minimum values ​​of the wall thickness T in the axial direction is large. Therefore, in the outer ring 10, deformation of the shape (especially deformation of the roundness of the raceway surface 10ca) may occur after heat treatment and machining. More specifically, the difference between the maximum and minimum values ​​of the diameter D3 may not fall within the range of JIS Class 0 (exceeding the upper limit of JIS Class 0).

[0043] However, according to the findings of the present inventors, if the difference between the maximum value and the minimum value of diameter D3 is less than or equal to twice the upper limit of JIS Class 0, the thickness variation of the outer ring 10 is 2 × 10 times the outer diameter D2. -4 If the difference is less than double, when the outer ring 10 is fitted into the housing, the shape of the outer ring 10 conforms to the shape of the housing, so that the difference between the maximum and minimum values ​​of diameter D3 falls within the range of JIS Class 0. Therefore, with the outer ring 10, even if the roundness of the raceway surface 10ca is compromised due to heat treatment or machining, it is possible to improve the roundness of the raceway surface 10ca by controlling the amount of thickness variation.

[0044] (Examples) To confirm the effect of the outer ring 10, multiple samples were prepared. In these samples, the difference between the maximum and minimum values ​​of diameter D3, and the amount of wall thickness variation were changed. Condition 1 is defined as the difference between the maximum and minimum values ​​of diameter D3 being greater than 1 and less than or equal to 2 times the upper limit of JIS Class 0. The amount of wall thickness variation of the outer ring is 2 × 10 of the outer diameter D2. -4Condition 2 is that the difference is less than or equal to twice the original value. After these samples were tight-fitted into the housing, the difference between the maximum and minimum values ​​of the diameter D3 was measured again. The roundness of the holes in the housing into which the samples were fitted was set to IT4 as defined in the JIS standard, and the fit tolerance was set to M7 as defined in the JIS standard. For these samples, the value obtained by dividing the outer diameter D2 by the inner diameter D1 was set to 1.09, and the value obtained by dividing the maximum value of the wall thickness T in the axial direction by the minimum value of the wall thickness T in the axial direction was set to 4.0.

[0045] [Table 1]

[0046] In Table 1, "A" means that for all of the samples measured, the difference between the maximum and minimum diameter D3 after fitting into the housing is less than or equal to the upper limit of JIS Class 0. In Table 1, "B" means that for some of the samples measured, the difference between the maximum and minimum diameter D3 after fitting into the housing exceeds the upper limit of JIS Class 0. In Table 1, "C" means that for all of the samples measured, the difference between the maximum and minimum diameter D3 after fitting into the housing exceeds the upper limit of JIS Class 0.

[0047] As shown in Table 1, when both conditions 1 and 2 were met, the evaluation of the difference between the maximum and minimum diameter D3 after fitting into the housing was A. On the other hand, when at least one of conditions 1 and 2 was not met, the evaluation of the difference between the maximum and minimum diameter D3 after fitting into the housing was B or less.

[0048] This comparison experimentally revealed that even when the value obtained by dividing the outer diameter D2 by the inner diameter D1 is 1.1 or less, if both conditions 1 and 2 are met, the outer ring 10 conforms to the housing when fitted into it, and the roundness of the raceway surface 10ca falls within the range of JIS Class 0.

[0049] While embodiments of the present invention have been described above, various modifications of these embodiments are possible. Furthermore, the scope of the present invention is not limited to the embodiments described above. The scope of the present invention is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims. [Industrial applicability]

[0050] The above embodiment is particularly advantageously applicable to the raceway rings (outer rings) of tapered roller bearings used, for example, in speed reducers. [Explanation of Symbols]

[0051] 100 Rolling bearing, 10 Outer ring, 10a First end face, 10b Second end face, 10c Inner diameter face, 10ca Raceway face, 10d Outer diameter face, 10e Flange, 20 Inner ring, 20a First end face, 20b Second end face, 20c Inner diameter face, 20d Outer diameter face, 20da Raceway face, 30 Tapered roller, 40 Cage, A Center axis, D1 Inner diameter, D2 Outer diameter, D3 Diameter, D4, D5 Inner diameter, S1 Preparation process, S2 Hardening process, S3 Tempering process, S4 Machining process, T Wall thickness.

Claims

1. It is a track wheel, The raceway has an inner diameter surface and an outer diameter surface that extend in the circumferential direction, which is along the circumference of the circle centered on the central axis of the raceway, One of the inner diameter surface and the outer diameter surface has a raceway surface, The value obtained by dividing the outer diameter of the raceway by the inner diameter of the raceway is 1.1 or less. The value obtained by dividing the maximum thickness of the raceway in the axial direction, which is along the central axis, by the minimum thickness of the raceway in the axial direction is 2.0 or greater. The difference between the maximum and minimum diameters of the raceway surface is greater than one and less than or equal to two times the upper limit of JIS Class 0. The thickness variation of the raceway is 2 × 10 of the outer diameter of the raceway. －４ The raceway ring is less than twice the size.

2. The raceway according to claim 1, wherein the value obtained by dividing the maximum thickness of the raceway in the axial direction by the minimum thickness of the raceway in the axial direction is 3.0 or more.

3. The aforementioned raceway ring is the outer ring of a tapered roller bearing, The inner diameter surface has the raceway surface, The raceway wheel according to claim 1 or claim 2, wherein the angle between the raceway surface and the axial direction is 35° or more and 55° or less.

4. The system comprises a first end face and a second end face, which are end faces in the axial direction, The distance between the raceway surface and the outer diameter surface in the radial direction, which is perpendicular to the axial direction, decreases as you move from the first end face side towards the second end face side. The raceway wheel according to claim 3, wherein a flange portion is formed on the inner diameter surface between the raceway surface and the second end surface, projecting inward in the radial direction.

5. The raceway ring according to any one of claims 1 to 4, wherein the raceway ring is formed of steel that has been hardened and tempered.

6. Outer ring and, Equipped with a conical roller, The outer ring has an inner diameter surface and an outer diameter surface that extend in the circumferential direction, which is along the circumference of a circle centered on the central axis of the outer ring, and a first end surface and a second end surface that are end surfaces in the axial direction, which is along the central axis. The inner diameter surface includes the raceway surface, The value obtained by dividing the outer diameter of the outer ring by the inner diameter of the outer ring is 1.1 or less. The value obtained by dividing the maximum thickness of the outer ring in the axial direction by the minimum thickness of the outer ring in the axial direction is 2.0 or greater. The difference between the maximum and minimum diameters of the raceway surface is greater than one and less than or equal to two times the upper limit of JIS Class 0. The amount of thickness variation of the outer ring is 2 × 10 of the outer diameter of the outer ring. －４ It is less than double, The angle between the raceway surface and the axial direction is 35° or more and 55° or less. The distance between the raceway surface and the outer diameter surface in the radial direction perpendicular to the axial direction decreases from the first end face side toward the second end face side. A tapered roller bearing wherein a flange portion is formed on the inner diameter surface between the raceway surface and the second end surface, projecting inward in the radial direction.

7. With additional internal support, The tapered roller bearing according to claim 6, wherein the value obtained by dividing the outer diameter of the outer ring by the inner diameter of the inner ring is 1.3 or less.

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