Follower bearing module

Abstract

This follower bearing module comprises a follower bearing and an attachment fixture. The follower bearing includes an inner member, an outer ring, and a plurality of rolling elements. The inner member includes a large-diameter part on which a first raceway surface is provided, and a shaft part that extends from the large-diameter part in an axial direction and is at least partially accommodated in an attachment hole. The shaft part is provided with a screw hole which is recessed in the axial direction and in which a screw groove is formed on the inner peripheral surface thereof. The attachment fixture includes: a body part that extends in the axial direction, has a screw thread formed on the outer peripheral surface thereof, and is fitted into the screw hole; and a head part that is provided at one axial-direction end of the body part and extends to the outside-diameter side. A strength-retaining part that retains the strength of the follower bearing is provided between the end part positioned on the first-raceway-surface side of the region in which the screw groove of the screw hole is formed in the axial direction and the axial-direction end part of the first raceway surface.

Description

Follower Bearing Module

[0001] The present disclosure relates to a follower bearing module. This application claims priority to Japanese Application No. 2024-97542, filed on June 17, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] A cam follower mounting structure used to mount a cam follower is known (see, for example, Patent Document 1). Also, a cam follower fixing structure used to fix a cam follower is known (see, for example, Patent Document 2). Also, a follower bearing module is known that includes a follower bearing, a mounting fixture that mounts the follower bearing to a mounting member, and a fastener that fastens the follower bearing and the mounting fixture together (see, for example, Patent Document 3).

[0003] Japanese Patent Application Laid-Open No. 10-2400 Japanese Patent Application Laid-Open No. 2000-346173 Japanese Patent No. 7410357

[0004] A follower bearing is attached and fixed to a mounting member so that the outer ring rotates. When attaching a follower bearing, it is preferable that the installation space at the mounting location be as small as possible. In other words, it is required to make the installation space of the follower bearing compact. It is also preferable that the attachment of the follower bearing can be achieved with a relatively simple configuration. Furthermore, it is required that the follower bearing have high load-bearing capacity.

[0005] Therefore, one of the objects is to provide a follower bearing module that can achieve a compact installation space, simple installation configuration, and high load resistance.

[0006] A follower bearing module according to the present disclosure is a follower bearing module for mounting a follower bearing to a mounting member having a mounting hole. It includes a follower bearing and a mounting fixture for mounting the follower bearing to the mounting member. The follower bearing includes an inner member having an annular first raceway surface on its outer peripheral surface, an outer ring having an annular second raceway surface on its inner peripheral surface that faces the first raceway surface, and a plurality of rolling elements arranged on an annular track along the first and second raceway surfaces so as to contact the first and second raceway surfaces. The inner member includes a large-diameter portion having the first raceway surface and a shaft portion extending axially from the large-diameter portion and at least a portion of which is received in the mounting hole. The shaft portion is provided with a threaded hole that is recessed axially and has a thread formed on its inner peripheral surface. The mounting fixture includes a body portion extending axially, having a screw thread formed on its outer peripheral surface, and being fitted into the threaded hole, and a head portion provided at one axial end of the body portion and extending toward the outer diameter. A strength retaining portion that maintains the strength of the follower bearing is provided between the end portion of the threaded hole located on the first raceway surface side of the region where the thread groove is formed in the axial direction and the axial end portion of the first raceway surface.

[0007] According to the follower bearing module, it is possible to achieve a compact installation space, easy installation, and high load resistance.

[0008] FIG. 1 is a schematic perspective view of a follower bearing module according to a first embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG. 1 . FIG. 3 is a schematic cross-sectional view taken along the line III-III in FIG. 1 . FIG. 4 is an exploded perspective view schematically illustrating the follower bearing module shown in FIG. 1 . FIG. 5 is a schematic perspective view of a shaft member. FIG. 6 is a schematic cross-sectional view of the shaft member. FIG. 7 is a schematic perspective view of a mounting fixture. FIG. 8 is a schematic rear view of the mounting fixture. FIG. 9 is a graph showing the relationship between the amount of displacement and the load when the axial length of the strength retaining portion is varied. FIG. 10 is a schematic cross-sectional view of a follower bearing module when the mounted member is relatively thick. FIG. 11 is a schematic perspective view of a follower bearing module according to a second embodiment of the present disclosure. FIG. 12 is a schematic cross-sectional view taken along the line XII-XII in FIG. 11 . FIG. 13 is a schematic cross-sectional view taken along the line XIII-XIII in FIG. 11 . FIG. 14 is an exploded perspective view schematically illustrating the follower bearing module shown in FIG. 11 . FIG. 15 is a schematic perspective view showing a portion of the follower bearing module according to the second embodiment. FIG. 16 is a schematic perspective view of a mounting fixture. FIG. 17 is a schematic rear view of the mounting fixture. FIG. 18 is a schematic perspective view of a follower bearing module according to the third embodiment of the present disclosure. FIG. 19 is a schematic cross-sectional view taken along the cross section indicated by XIX-XIX in FIG. 18 . FIG. 20 is an exploded perspective view schematically illustrating the follower bearing module shown in FIG. 18 . FIG. 21 is a schematic perspective view of a mounting fixture included in the follower bearing module according to the third embodiment. FIG. 22 is a schematic rear view of the mounting fixture shown in FIG. 21 . FIG. 23 is a schematic perspective view of a follower bearing module according to the fourth embodiment of the present disclosure. FIG. 24 is a schematic cross-sectional view taken along the cross section indicated by XXIV-XXIV in FIG. 23 . FIG. 25 is an exploded perspective view schematically illustrating the follower bearing module shown in FIG. 23 . Fig. 26 is a schematic perspective view of a mounting fixture included in a follower bearing module according to embodiment 4. Fig. 27 is a schematic rear view of the mounting fixture shown in Fig. 26 .

[0009] [Summary of the embodiment] The follower bearing module disclosed herein is a follower bearing module for mounting a follower bearing to a mounting member having a mounting hole. It includes a follower bearing and a mounting fixture for mounting the follower bearing to the mounting member. The follower bearing includes an inner member having a first annular raceway surface on its outer peripheral surface, an outer ring having a second annular raceway surface on its inner peripheral surface that faces the first raceway surface, and a plurality of rolling elements arranged on an annular raceway that follows the first and second raceway surfaces and contacts the first and second raceway surfaces. The inner member includes a large-diameter portion having the first raceway surface and a shaft portion extending axially from the large-diameter portion and at least a portion of which is received in the mounting hole. The shaft portion is provided with a threaded hole that is recessed axially and has a thread groove formed on its inner peripheral surface. The mounting device includes a body portion that extends in the axial direction, has a screw thread formed on its outer peripheral surface, and is fitted into the threaded hole, and a head portion that is provided at one axial end of the body portion and extends toward the outer diameter. A strength retaining portion that maintains the strength of the follower bearing is provided between an end portion of the threaded hole in the axial direction that is located on the first raceway surface side of the region where the thread groove is formed and an axial end portion of the first raceway surface.

[0010] A follower bearing is attached and fixed to a workpiece, such as a driven member, with its outer ring rotating. Specifically, the follower bearing is attached by receiving an axially extending portion called a stud in a mounting hole provided in the workpiece. The follower bearing is then fixed to the workpiece without interfering with the rotation of the outer ring. When attaching a follower bearing, compact installation space and a simple installation configuration are required. Furthermore, high load-bearing capacity is also required.

[0011] The follower bearing module disclosed herein is comprised of a follower bearing and a mounting fixture, enabling installation with a simple configuration. Furthermore, the mounting fixture and follower bearing can be fastened together by engaging the threads formed on the body of the mounting fixture with the threaded hole formed on the shaft portion of the inner member, thereby attaching the follower bearing to the mounted member. In this case, the mounted member can be sandwiched between the head of the mounting fixture and the follower bearing. Therefore, when installing the mounting fixture, a space with an axial length approximately equal to the thickness of the head is sufficient, allowing for more compact installation space than fastening using a nut or the like. Furthermore, a strength retaining portion that maintains the strength of the follower bearing is provided between the axial end of the threaded hole located on the first raceway surface side of the region where the thread groove is formed and the axial end of the first raceway surface. This allows the strength retaining portion to withstand a large load even when applied from the outer diameter side of the outer ring, reducing the risk of damage to the inner member. Therefore, the load-bearing capacity can be increased. As described above, the follower bearing module of the present disclosure can achieve a compact installation space, simple installation configuration, and high load resistance.

[0012] In the above follower bearing module, the large diameter portion may be provided with a lubricant supply hole extending from the end opposite the side where the shaft portion is located in the axial direction to the first raceway surface. This allows the lubricant supply hole to be used to supply lubricant such as lubricating oil or grease from the outside to the inside of the follower bearing, specifically, to the raceways in which the rolling elements roll within the follower bearing. This ensures smooth rolling of the rolling elements for a longer period of time, making it easier to extend the life of the follower bearing.

[0013] In the follower bearing module, the lubricant supply hole may include a first hole that has an opening on the axial side opposite to the side where the shaft portion is disposed and is recessed in the axial direction, and a second hole that extends from the first hole toward the outer diameter side and reaches the first raceway surface. This allows the first hole and the second hole to be used to appropriately supply lubricant into the raceway in which the rolling elements roll. This enables more appropriate supply of lubricant.

[0014] In the follower bearing module, a refill plug may be disposed in the lubricant refill hole. By doing so, the refill plug can be used to ensure a more appropriate lubricant supply path within the follower bearing. This can more reliably ensure smooth rolling of the rolling elements.

[0015] In the follower bearing module, the axial length of the strength retaining portion may be 0.1 to 1 times the diameter of the shaft portion. This makes it possible to ensure high load-bearing capacity while preventing the follower bearing module from becoming too large in the axial direction. Therefore, it is possible to achieve both a compact installation space and high load-bearing capacity at a high level.

[0016] In the follower bearing module, the axial length of the region where the thread groove is formed may be 1.5 to 3 times the thread diameter of the body portion. By making the length 1.5 times or more, the fastening force of the mounting device in the body portion can be reliably ensured. Furthermore, by making the length 3 times or less, the fitting region of the body portion can be lengthened in the axial direction while compactifying the installation space. Therefore, loosening of the mounting device during operation can be easily suppressed.

[0017] In the above-described follower bearing module, the inner member may be constructed as a single unit, which improves productivity compared to an inner member constructed by combining a plurality of parts, and also makes it easier to maintain high rigidity of the inner member itself.

[0018] In the follower bearing module, the grain flows of the inner member may be aligned in the same direction. Such an inner member can be manufactured by, for example, a rolling process. Such an inner member is more preferably used because of its high rigidity.

[0019] In the follower bearing module, the material of the inner member may be low-carbon steel. The inner member may be carburized and quenched. This increases the strength of the entire inner member. This increases the strength of the first raceway surface as well as the strength of the strength retaining portion.

[0020] In the above follower bearing module, the material of the inner member may be stainless steel. The inner member may be subjected to vacuum quenching. This increases the strength of the inner member and provides a follower bearing module with excellent corrosion resistance.

[0021] In the above follower bearing module, the follower bearing may further include a cage that holds the plurality of rolling elements. The cage may include a plurality of column sections arranged between the rolling elements, and an annular connecting section that is connected to one axial end of the column sections and connects the plurality of column sections. In this manner, the cage can appropriately guide the rolling elements while maintaining appropriate circumferential spacing between the rolling elements. This can ensure smooth rotation of the outer ring included in the follower bearing.

[0022] In the above-described follower bearing module, at least one of the follower bearing and the mounting fixture may be provided with an anti-rotation mechanism that prevents rotation of the components. By doing so, when fastening the follower bearing and the mounting fixture, the anti-rotation mechanism can be used to prevent rotation of at least a portion of the components of either the follower bearing or the mounting fixture. Therefore, such a follower bearing module can achieve a compact installation space and improved convenience when installing the follower bearing.

[0023] In the above-described follower bearing module, at least one of the follower bearing and the mounting fixture may be provided with an anti-slip mechanism that prevents slippage of the rotating member. By doing so, when either the follower bearing or the mounting fixture is rotated to fasten the follower bearing to the mounting fixture, slippage of the rotating member can be prevented and the rotating member can be rotated reliably. Therefore, such a follower bearing module can achieve a compact installation space and improved convenience when installing the follower bearing.

[0024] In the follower bearing module, the outer shape of the head may be polygonal when viewed in the axial direction. This allows the polygonal head to be fitted using a wrench with an open tip, making it easier to have it function as at least one of an anti-rotation mechanism and an anti-slip mechanism. This makes installation easier.

[0025] In the follower bearing module, the outer shape of the head may be hexagonal when viewed in the axial direction, which allows the hexagonal head to be more appropriately fitted using a hexagonal wrench with an open tip, making it easier to function as at least one of the anti-rotation mechanism and the anti-slip mechanism.

[0026] The follower bearing module of the present disclosure is a follower bearing module for mounting a follower bearing to a mounting member provided with a mounting hole. The follower bearing module includes a follower bearing and a mounting fixture for mounting the follower bearing to the mounting member. The follower bearing includes an inner member having an annular first raceway surface on its outer peripheral surface, an outer ring having an annular second raceway surface on its inner peripheral surface that faces the first raceway surface, and a plurality of rolling elements arranged on an annular track along the first and second raceway surfaces so as to contact the first and second raceway surfaces. The inner member includes a large diameter portion provided with the first raceway surface, and a shaft portion extending axially from the large diameter portion and at least a portion of which is received in the mounting hole. The shaft portion is provided with a threaded hole that is recessed in the axial direction and has a thread groove formed on its inner peripheral surface. The mounting tool includes a body portion that extends in the axial direction, has a thread formed on its outer peripheral surface, and is fitted into the screw hole, and a head portion that is provided at one axial end of the body portion and extends outwardly. The outer shape of the head portion is polygonal when viewed in the axial direction.

[0027] This follower bearing module, which is comprised of a follower bearing and a mounting fixture, allows for simple installation. Furthermore, the mounting fixture and follower bearing can be fastened together by engaging a thread formed in the body of the mounting fixture with a threaded hole formed in the shaft of the inner member, thereby attaching the follower bearing to the mounting member. In this case, the mounting member can be sandwiched between the head of the mounting fixture and the follower bearing. Therefore, when installing the mounting fixture, only a space with an axial length equivalent to the thickness of the head is required, allowing for more compact installation space than fastening using a nut or the like. Furthermore, because the external shape of the head is polygonal when viewed in the axial direction, the head can function as at least one of an anti-rotation mechanism and an anti-slip mechanism. This facilitates installation.

[0028] In the follower bearing module, the head may have a hexagonal outer shape, which allows the hexagonal head to be more appropriately fitted using a hexagonal wrench with an open tip, making it easier to function as at least one of the anti-rotation mechanism and the anti-slip mechanism.

[0029] In the above-mentioned follower bearing module, the surface of the head in the axial direction where the body is not provided may be made of a flat surface. This follower bearing module can suppress a decrease in the strength of the mounting fixture. Therefore, the strength of the follower bearing module itself can be improved.

[0030] [Specific Example of Embodiment] Next, an example of a specific embodiment of the follower bearing module of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0031] First Embodiment First, a first embodiment of the present disclosure will be described. FIG. 1 is a schematic perspective view of a follower bearing module according to the first embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG. 1. FIG. 2 is a cross-sectional view taken along a plane including a rotation axis 16a (described later) and parallel to the Y-Z plane. FIG. 3 is a schematic cross-sectional view taken along the line III-III in FIG. 1. FIG. 3 is a cross-sectional view taken along a plane including a rotation axis 16a and parallel to the X-Y plane. FIG. 4 is an exploded perspective view schematically illustrating the follower bearing module shown in FIG. 1. A mounting member (described later) is not shown in FIG. 4. In FIG. 1 and the following figures, the Y direction indicates the axial direction of the follower bearing. The X and Z directions indicate radial directions from the center of the follower bearing when viewed from the axial direction. In other words, the X and Z directions are directions when the direction of the central rotation axis of the follower bearing is defined as the Y direction. The X direction is a direction perpendicular to the Z direction in a plane perpendicular to the axial direction.

[0032] 1, 2, 3 and 4, the follower bearing module 10a in the first embodiment includes a follower bearing 11a and a mounting fixture 70a. The follower bearing module 10a is mounted to a mounted member 90a having a predetermined thickness, such as a driven member. In FIG. 1, the mounted member 90a is indicated by a dashed line. The mounted member 90a is provided with a mounting hole 93a that penetrates from a first surface 91a, which is a surface on one side in the thickness direction, to a second surface 92a, which is a surface on the other side in the thickness direction. The mounted member 90a is plate-shaped, and its thickness, i.e., the length in the Y direction from the first surface 91a to the second surface 92a, is a thickness T １ The follower bearing 11a is attached to the attached member 90a using this attachment hole 93a. The attachment hole 93a is a round hole that penetrates straight in the Y direction, which is the axial direction of the follower bearing 11a. In other words, the inner wall surface 94a that constitutes the attachment hole 93a is a cylindrical surface. Such an attachment hole 93a can be formed by drilling a so-called straight hole, and therefore can be formed more easily than, for example, an attachment hole with a step on the inner wall surface.

[0033] First, a brief description of the configuration of the follower bearing 11a will be given. The follower bearing 11a includes a shaft member 12a as an inner member, an outer ring 13a, a plurality of rollers 14a as rolling elements, a cage 15a that holds the rollers 14a, a refill plug 61a, a pair of seal members 66a, 67a, and a side plate 19a that is a ring. In Figures 2 and 3, the rotation axis 16a, which is the central axis of the shaft member 12a, is shown by a dashed line.

[0034] FIG. 5 is a schematic perspective view of the shaft member 12a. FIG. 6 is a schematic cross-sectional view of the shaft member 12a. FIG. 6 is a cross-sectional view taken along the same plane as FIG. 2. Referring to both FIGS. 5 and 6, the shaft member 12a includes a rod-shaped main body 17a and a flange 18a formed at one end of the main body 17a and having a diameter larger than that of the main body 17a. The main body 17a has a first end face 21a at one end in the axial direction and a second end face 22a at the other end opposite the first end face 21a. The first end face 21a has a circular planar shape. The second end face 22a also has a circular planar shape. An outer peripheral surface 23a of the annular flange 18a faces the outer ring 13a.

[0035] The main body 17a includes a hollow cylindrical shaft portion 31a and a large-diameter portion 32a that is larger in diameter than the shaft portion 31a and is located axially between the shaft portion 31a and the flange portion 18a. The outer diameter of the shaft portion 31a, which faces the inner wall surface 94a of the mounting hole 93a of the mounted member 90a, is large enough to fit into the mounting hole 93a of the mounted member 90a. That is, when the follower bearing 11a is mounted, the outer peripheral surface 37a of the shaft portion 31a faces the inner wall surface 94a of the mounting hole 93a. The outer diameter of the large-diameter portion 32a is smaller than the outer diameter of the flange portion 18a. A first raceway surface 33a having a cylindrical shape is formed on the outer peripheral surface of the large-diameter portion 32a. That is, the shaft member 12a has an annular first raceway surface 33a on its outer peripheral surface. In this embodiment, the main body 17a includes a large diameter portion 32a provided with a first raceway surface 33a, and a shaft portion 31a extending axially from the large diameter portion 32a and accommodated in the mounting hole 93a. A stepped surface 36a extending radially is formed on the end surface of the large diameter portion 32a on the shaft portion 31a side in the axial direction.

[0036] The outer peripheral surface 37a of the shaft portion 31a is a cylindrical surface. The shaft portion 31a is provided with a threaded hole 38a recessed in the axial direction. A thread groove 39a is formed in the threaded hole 38a of the shaft portion 31a. That is, the thread groove 39a is provided on the inner peripheral surface of the shaft portion 31a. The axial length of the region where the thread groove 39a is formed is length D １ The axial length D of the region where the screw groove 39a is provided is １is 1.5 to 3 times the diameter of the thread of the body 71a of the mounting fixture 70a, which will be described later. １ It is shown as follows.

[0037] The shaft member 12a is provided with a lubricant supply hole 24a for supplying lubricant to the follower bearing 11a. The lubricant supply hole 24a extends from a first end face 21a, which is the end opposite to the side where the shaft portion 31a is located in the axial direction, to the first raceway surface 33a. In this embodiment, the lubricant supply hole 24a includes a first hole 25a and a second hole 26a.

[0038] The first hole 25a is provided on the axial side opposite to the position where the shaft portion 31a is disposed. The first hole 25a is provided so as to be recessed in the axial direction from the first end face 21a. The first hole 25a has an opening on the axial side opposite to the side where the shaft portion 31a is disposed. The opening of the first hole 25a on the first end face 21a side is a circular hole. In this embodiment, only one first hole 25a is provided.

[0039] In the axial direction, the inner diameter of the first region 27a of the first hole 25a located on the first end face 21a side is larger than the inner diameter of the second region 28a adjacent to the first region 27a at the axial center. Furthermore, the inner diameter of the third region 29a adjacent to the second region 28a at the axial center is smaller than the inner diameter of the second region 28a. That is, the inner diameter of the first hole 25a gradually decreases toward the axial center. The portion of the first region 27a adjacent to the second region 28a has a hexagonal socket shape that can be fitted with a hexagonal wrench. The hexagonal socket-shaped portion of the first region 27a of the lubricant supply hole 24a functions as a rotation prevention mechanism 40a that prevents rotation of the member. Specifically, the hexagonal socket-shaped portion of the anti-rotation mechanism 40a functions to prevent rotation of the shaft member 12a, which is part of the inner member, when attaching the follower bearing module 10a to the attached member 90a. In this case, a hexagonal socket wrench is inserted into the hexagonal socket-shaped portion and fixed to prevent rotation of the shaft member 12a, and the mounting fixture 70a is rotated to fasten and attach the follower bearing module 10a to the attached member 90a. The hexagonal socket-shaped portion also functions as an anti-slip mechanism 50a, which prevents slippage of the rotating member. In this case, the mounting fixture 70a is fixed so as not to rotate, and a hexagonal socket wrench is inserted into the hexagonal socket-shaped portion and the shaft member 12a is rotated to fasten and attach the follower bearing module 10a to the attached member 90a. At this time, the hexagonal socket-shaped portion can be properly fitted with a hexagonal wrench when inserted, thereby functioning as an anti-slip mechanism 50a that prevents slippage of the shaft member 12a, which is the member to be rotated. The depth of the first hole 25a, i.e., the axial length of the first hole 25a from the first end face 21a, is shorter than the length from the first end face 21a to the axial end of the first raceway surface 33a. Note that no thread grooves are provided on the inner peripheral surface of the first hole 25a.

[0040] The second hole 26a is provided so as to extend radially outward from the first hole 25a to the first raceway surface 33a. The second hole 26a is provided so as to extend radially straight from the axially central region of the first hole 25a. The second hole 26a is a circular hole. The second hole 26a is provided so as to open a portion of the first raceway surface 33a. In this embodiment, only one second hole 26a is provided. The first hole 25a and the second hole 26a included in the lubricant supply hole 24a can be used to supply lubricant from outside the follower bearing 11a to the first raceway surface 33a side.

[0041] The replenishment plug 61a is disposed in the first hole 25a of the shaft member 12a, which serves as the inner member. Specifically, the replenishment plug 61a is attached so as to fit into the third region 29a of the first hole 25a. The replenishment plug 61a is hollow and cylindrical, and includes a guide hole 62a having a tapered inner wall surface, an injection hole 63a having a smaller diameter than the guide hole 62a, and a discharge hole 64a having a larger diameter than the injection hole 63a. The guide hole 62a is configured so that its diameter decreases from the opening at the axial end toward the axially inward side. In the replenishment plug 61a, the guide hole 62a faces the first end face 21a in the axial direction.

[0042] An example of the supplying method is as follows. During supplying, the tip of a supplying device (not shown) is fitted into the guide hole 62a. When the supplying device supplies lubricant via the injection hole 63a and the discharge hole 64a, the lubricant passes from the first hole 25a through the second hole 26a and reaches the first raceway surface 33a. The lubricant is then supplied into the raceway along which the rollers 14a roll. Supplying is performed in this manner.

[0043] In this embodiment, the shaft member 12a is made of low-carbon steel, i.e., carbon steel with a carbon content of 0.25% by mass or less. The shaft member 12a is carburized and quenched. In this embodiment, the shaft member 12a is manufactured by rolling. The grain flows of the shaft member 12a are aligned in the same direction.

[0044] The outer ring 13a has an annular shape. The outer ring 13a has an annular second raceway surface 51a on its inner circumferential surface, which faces the first raceway surface 33a. The outer ring 13a also has an annular outer circumferential surface 52a, a first end face 53a, and a second end face 54a. In this embodiment, the outer circumferential surface 52a is cylindrical except for both axially chamfered ends. In the axial direction, the radial thickness of a central portion 55a of the outer ring 13a, on which the second raceway surface 51a is provided, is greater than the radial thickness of one end 56a including the first end face 53a and the radial thickness of the other end 57a including the second end face 54a. The inner circumferential surface of the one end 56a including the first end face 53a is recessed radially outward to accommodate the flange portion 18a of the shaft member 12a. The inner peripheral surface of the other end 57a, including the second end face 54a, is recessed toward the outer diameter side to receive the side plate 19a. That is, the outer ring 13a is configured so that the axial central portion 55a is thick and the axial one end 56a and the other end 57a are thin.

[0045] The outer ring 13a is made of steel. Examples of steel that can be used to form the outer ring 13a include bearing steel, carbon steel for mechanical structures, alloy steel for mechanical structures, and stainless steel. The outer ring 13a may also be quench-hardened.

[0046] The cage 15a has an annular shape. In this embodiment, the cage 15a is made of steel. However, the cage 15a may also be made of resin. The cage 15a is disposed concentrically with the shaft member 12a and the outer ring 13a in the space between the shaft member 12a and the outer ring 13a. The cage 15a includes a plurality of column portions 45a each disposed between the rollers 14a in the circumferential direction, and a pair of connecting portions 46a, 47a connecting the column portions 45a. Each of the pair of connecting portions 46a, 47a is annular and provided at both axial ends of the column portions 45a. A plurality of pockets 48a are disposed at equal intervals in the circumferential direction in the cage 15a. One roller 14a is disposed in each of the plurality of pockets 48a. By being held by the cage 15a in this manner, the rollers 14a are arranged on an annular track along the first raceway surface 33a and the second raceway surface 51a so as to contact the first raceway surface 33a and the second raceway surface 51a. The rollers 14a have a solid cylindrical shape. The rollers 14a include a cylindrical outer peripheral surface 58a and a pair of flat end surfaces 59a, 60a. The end surfaces 59a, 60a of the rollers 14a may be spherical. The outer peripheral surface 58a of the rollers 14a contacts the first raceway surface 33a and the second raceway surface 51a. The rollers 14a are made of steel, such as bearing steel or stainless steel. The rollers 14a may be quench-hardened.

[0047] The pair of seal members 66a, 67a are arranged on both axial end sides of the outer ring 13a. The seal member 66a is attached so as to contact the outer peripheral surface 23a of the flange portion 18a. The seal member 67a is attached so as to contact the outer peripheral surface 43a of the side plate 19a (described later). The pair of seal members 66a, 67a seal the inside of the follower bearing 11a.

[0048] The side plate 19a is coaxially mounted on the main body 17a and circumferentially surrounds a portion of the outer circumferential surface of the main body 17a. The annular side plate 19a has a first end face 41a, which is one end face, a second end face 42a, which is the other end face, an outer circumferential surface 43a, and an inner circumferential surface 44a. The first end face 41a and the second end face 42a are parallel. The outer circumferential surface 43a and the inner circumferential surface 44a are concentric cylindrical surfaces. The side plate 19a is positioned so that the first end face 41a contacts the stepped surface 36a, which is the end face of the large diameter portion 32a on the shaft portion 31a side. The inner diameter of the side plate 19a is slightly larger than the outer diameter of the shaft portion 31a in the region that fits into the mounting hole 93a. One end of the shaft 31a has a portion with a larger outer diameter than the region that fits into the mounting hole 93a, and the side plate 19a is press-fit into this larger outer diameter portion of the shaft 31a and fixed to the large diameter portion 32a. Note that part or all of the side plate 19a may be quench-hardened. Note that the thickness of the side plate 19a, i.e., the length from the first end face 41a to the second end face 42a in the Y direction, is indicated by thickness C.

[0049] Next, the configuration of the mounting fixture 70a will be described. Fig. 7 is a schematic perspective view of the mounting fixture 70a. Fig. 8 is a schematic rear view of the mounting fixture 70a. Fig. 8 is a view of the mounting fixture 70a as seen in the direction opposite to the arrow Y.

[0050] 7 and 8 , the mounting fixture 70a includes a body portion 71a and a head portion 72a. The body portion 71a has a shape extending in the axial direction. A screw thread 74a is formed on an outer peripheral surface 73a of the body portion 71a. The body portion 71a is fitted into the screw groove 39a. The head portion 72a is provided at one axial end of the body portion 71a. The head portion 72a has a shape extending toward the outer diameter side. In this embodiment, the head portion 72a is flat. The head portion 72a does not have any holes or irregularities except for an area where a hexagonal hole, described below, is formed. The head portion 72a includes a surface (first surface) 75a located on one side in the thickness direction (axial direction) and a surface (second surface) 76a located on the other side in the thickness direction. The body portion 71a is provided on the surface 76a side. The mounting fixture 70a having such a configuration can be manufactured by, for example, forging, specifically cold forging, which increases the degree of freedom in design and allows the mounting fixture 70a to be designed in accordance with the needs of the user.

[0051] The outer shape of the head 72a is a circular shape with a part cut out when viewed from the axial direction (Y direction) which is the thickness direction of the head 72a (see, in particular, FIG. 8). １ and a first portion 81a as the rotation prevention mechanism 40a, the first portion 81a having a second length L ２and a second portion 82a having a shape of 1 / 2" x 1 / 2". The first portion 81a also functions as an anti-slip mechanism 50a that prevents slippage of the rotating member. Here, the radial length is the length from the rotation axis 16a to the outer circumferential surface. The outer circumferential surface 83a of the head 72a corresponding to the first portion 81a is a flat surface. The outer circumferential surface 84a of the head 72a corresponding to the second portion 82a is an arcuate surface. Multiple first portions 81a (two in this embodiment) are provided, and the outer circumferential surfaces 83a of the heads 72a corresponding to the first portions 81a are arranged parallel to each other with a circumferential gap between them. The outer circumferential surfaces 83a of the first portions 81a and the outer circumferential surfaces 84a of the second portions 82a are continuous with each other. In other words, the outer circumferential surface of the head 72a has a shape obtained by cutting a circular outer circumferential surface as viewed in the axial direction at two symmetrical locations equidistant from the rotation axis 16a in the X direction by a plane that includes the rotation axis 16a and is parallel to the Y-Z plane. A tightening tool, such as a wrench with an open tip, can be attached to the two first portions 81a from the outer diameter side to clamp the heads 72a as a tool to prevent rotation of the mounting fixture 70a. The first portions 81a, which function as the anti-rotation mechanism 40a, function to prevent rotation of the mounting fixture 70a when attaching the follower bearing module 10a to the mounting base 90a. In this case, a tightening tool is attached to the pair of first portions 81a to fix the mounting fixture 70a so as to prevent rotation, and the shaft member 12a included in the follower bearing 11a is rotated to fasten the follower bearing module 10a to the mounting base 90a. The pair of first portions 81a also function as anti-slip mechanisms 50a to prevent slippage of the rotating member. In this case, the shaft member 12a is fixed so as to prevent rotation, and a tightening tool is attached to the pair of first portions 81a to rotate the mounting fixture 70a to attach the follower bearing module 10a to the mounting base 90a. At this time, the pair of first parts 81a function as an anti-slip mechanism 50a that prevents the mounting fixture 70a, which is the rotating member, from slipping, because the part of the wrench whose tip is open when the tightening tool is attached can be properly fitted into the pair of first parts 81a.

[0052] The head 72a includes a hole 85a recessed from one surface in the thickness direction as the anti-rotation mechanism 40a. That is, the hole 85a is recessed in the axial direction. The hole 85a has portions with different diameters. In this embodiment, the hole 85a is a hexagonal socket. A hexagonal wrench, which serves as a tool to prevent rotation of the mounting fixture 70a, can be fitted into the hole 85a from the axial direction. The hole 85a also functions as an anti-slip mechanism 50a that prevents the rotating member from slipping. The function of the hexagonal socket hole 85a as the anti-rotation mechanism 40a and the anti-slip mechanism 50a is similar to that of the hexagonal socket-shaped portion provided in the first hole 25a described above.

[0053] Here, the configuration of the shaft member 12a will be further described. A strength retaining portion 34a that retains the strength of the follower bearing 11a is provided between an end portion 35a located on the first raceway surface 33a side of the region of the threaded hole 38a where the thread groove 39a is formed and the axial end portion of the first raceway surface 33a. In this embodiment, the axial end portion of the first raceway surface 33a is the portion where the step surface 36a is located. The axial length of the strength retaining portion 34a is length B １ That is, in the axial direction, the end portion 35a in which the screw groove 39a is formed does not reach the end portion of the first raceway surface 33a. １ is 0.1 to 1 times the diameter of the shaft portion 31a. The diameter of the shaft portion 31a is the length U １ It is shown as follows.

[0054] Next, an example of the mounting process for mounting the follower bearing 11a to the mounting member 90a will be briefly described. First, the shaft portion 31a of the body 17a of the assembled follower bearing 11a is advanced in the direction indicated by arrow Y and inserted into the mounting hole 93a of the mounting member 90a. At this time, the inner wall surface 94a of the mounting hole 93a and the outer peripheral surface 37a of the shaft portion 31a face each other in the radial direction. Furthermore, the second end surface 42a of the side plate 19a and the first surface 91a of the mounting member 90a come into contact in the axial direction. Note that a gap is formed between the second end surface 54a of the outer ring 13a and the first surface 91a of the mounting member 90a in the axial direction.

[0055] Thereafter, the mounting fixture 70a is attached to the mounting member 90a from the axially opposite side of the follower bearing 11a, i.e., from the second surface 92a side of the mounting member 90a. At this time, the mounting fixture 70a is inserted while being rotated in the direction opposite to the arrow Y so that the threads of the body 71a fit into the thread groove 39a of the screw hole 38a.

[0056] At this time, the attachment device 70a is tightened to secure the follower bearing 11a to the attachment workpiece 90a while preventing rotation of the follower bearing 11a using the anti-rotation mechanism 40a in the hexagonal recessed portion of the first hole 25a. Specifically, a hex wrench is inserted into the first hole 25a to secure the follower bearing 11a so that it does not rotate. If there is an obstacle on the second surface 92a of the attachment workpiece 90a, the hex wrench is inserted into the hole 85a of the attachment device 70a and fitted to rotate the attachment device 70a. If there is no obstacle on the second surface 92a of the attachment workpiece 90a, the two first portions 81a are used to clamp and hold the heads 72a using a tightening tool such as a wrench with an open tip, and the attachment device 70a is rotated. At this time, the pair of first portions 81a function as the anti-slip mechanism 50a. In this way, the attachment tool 70a is rotated and tightened while preventing the follower bearing 11a from rotating, and the follower bearing 11a is attached to the attachment member 90a.

[0057] The follower bearing module 10a configured as described above is composed of the follower bearing 11a and the mounting fixture 70a, allowing for simple installation. Furthermore, the mounting fixture 70a and the follower bearing 11a can be fastened together by engaging the threads formed on the body portion 71a of the mounting fixture 70a with the threaded hole 38a formed in the shaft portion 31a of the shaft member 12a, which is the inner member, to mount the follower bearing 11a to the mounted member 90a. In this case, the mounted member 90a can be mounted by sandwiching it between the head portion 72a of the mounting fixture 70a and the follower bearing 11a. Therefore, when installing the mounting fixture 70a, the axial length only requires a space approximately equal to the thickness of the head portion 72a, allowing for more compact installation space than when using a nut or the like for fastening. Furthermore, a strength retaining portion 34a that maintains the strength of the follower bearing 11a is provided between the axial end of the threaded hole 38a, which is located on the first raceway surface 33a side of the region where the thread groove 39a is formed, and the axial end of the first raceway surface 33a. This allows the strength retaining portion 34a to withstand a large load even when applied from the outer diameter side of the outer ring 13a, reducing the risk of damage to the shaft member 12a. This increases the load-bearing capacity. As described above, the follower bearing module 10a of the present disclosure can achieve a compact installation space, simple installation, and high load-bearing capacity.

[0058] In particular, in the case of the technology disclosed in Patent Document 3, reducing the size of the follower bearing results in a reduction in the diameter of the bolt used as a fastener. This reduces the tightening torque, which may cause the bolt to loosen during operation. However, with the above-described configuration, even if the size of the follower bearing 11a is reduced, the diameter of the body portion 71a and the diameter of the shaft portion 31a of the mounting fixture 70a do not need to be significantly reduced. Therefore, the above-described follower bearing module 10a is particularly effective when the size is small.

[0059] In this embodiment, the large diameter portion 32a is provided with a lubricant supply hole 24a that extends from the first end face 21a, which is the end opposite the side where the shaft portion 31a is located in the axial direction, to the first raceway surface 33a. Therefore, the lubricant supply hole 24a can be used to supply lubricant such as lubricating oil or grease from the outside to the inside of the follower bearing 11a, specifically, to the raceway where the rollers 14a roll within the follower bearing 11a. This ensures smooth rolling of the rollers 14a for a longer period of time, facilitating a longer lifespan.

[0060] In this embodiment, the lubricant supply hole 24a has an opening on the axial side opposite the side where the shaft portion 31a is disposed, and includes a first hole 25a recessed in the axial direction, and a second hole 26a extending radially outward from the first hole 25a to the first raceway surface 33a. Therefore, the first hole 25a and the second hole 26a can be used to appropriately supply lubricant to the raceway in which the rollers 14a roll. This allows for more appropriate supply of lubricant.

[0061] In this embodiment, a refill plug 61a is disposed in the lubricant refill hole 24a. Therefore, by utilizing the refill plug 61a, a more appropriate lubricant supply path can be secured within the follower bearing 11a, thereby more reliably ensuring smooth rolling of the rollers 14a.

[0062] In this embodiment, the axial length of the strength retaining portion 34a is 0.1 to 1 times the diameter of the shaft portion 31a. This ensures high load-bearing capacity while preventing the follower bearing module 10a from becoming too large in the axial direction. This makes it possible to achieve both a compact installation space and high load-bearing capacity at a high level.

[0063] Here, a test was conducted on the strength of the strength retaining portion 34a. The test method is as follows. With the inner member (shaft member 12a) attached to the attached member 90a, the displacement of the first raceway surface 33a was measured when a load was applied to the first raceway surface 33a in a direction perpendicular to the rotation axis. The direction of the applied load is indicated by arrow V in FIG. 2. FIG. 9 is a graph showing the relationship between the displacement and the load when the axial length of the strength retaining portion 34a is changed. In FIG. 9, the horizontal axis represents the displacement (mm), and the vertical axis represents the applied load (kN). In FIG. 9, the dashed line represents the case where the axial length of the strength retaining portion 34a is 0.5 mm, and the solid line represents the case where the axial length of the strength retaining portion 34a is 2.5 mm. The dimension B shown in FIG. 9 is the above-mentioned length B １ and length B, which will be described later ２ In this case, the diameter of shaft portion 31a is 8 mm, and when the axial length of strength retaining portion 34a is 0.5 mm, this corresponds to 0.06 times the diameter of shaft portion 31a, and when the axial length of strength retaining portion 34a is 2.5 mm, this corresponds to 0.31 times the diameter of shaft portion 31a.

[0064] 9, when the length of the strength retaining portion 34a is 0.5 mm, the strength retaining portion 34a can withstand a load of up to 15 kN, and when the length of the strength retaining portion 34a is 2.5 mm, the strength retaining portion 34a can withstand a load of up to 25 kN.

[0065] In this embodiment, the axial length of the region where the thread groove 39a is formed is 1.5 to 3 times the thread diameter of the body portion 71a. By making this length 1.5 times or more, the fastening force of the body portion 71a of the mounting device 70a can be reliably ensured. Furthermore, by making this length 3 times or less, the fitting region of the body portion 71a can be elongated in the axial direction while compacting the installation space. Therefore, loosening of the mounting device 70a during operation can be more easily prevented.

[0066] Furthermore, if the region in which the thread groove 39a is formed is relatively long, the follower bearing module 10a can be configured to be attachable to workpieces of various thicknesses. FIG. 10 is a schematic cross-sectional view of the follower bearing module 10a when the workpiece is relatively thick. FIG. 10 corresponds to the cross-section shown in FIG. 2. Referring to FIG. 10, the workpiece 90b has a mounting hole 93b that penetrates from the first surface 91b to the second surface 92b. The follower bearing 11b is attached to the workpiece 90b using this mounting hole 93b. The inner wall surface 94b that constitutes the mounting hole 93b is a cylindrical surface. Here, the length between the first surface 91b and the second surface 92b in the Y direction is longer than the length between the first surface 91a and the second surface 92a of the workpiece 90a in the first embodiment. In this way, even if the workpiece 90b is relatively thick, the thread engagement of the body portion 71a can be maintained and the follower bearing module 11b can be fitted into the thread groove 39a. Therefore, it can be attached to the attached member 90b of various thicknesses.

[0067] In this embodiment, the shaft member 12a is constructed as a single unit, which improves productivity compared to a shaft member 12a constructed by combining multiple parts, and also makes it easier to maintain high rigidity of the shaft member 12a itself.

[0068] In this embodiment, the grain flows of the shaft member 12a are aligned in the same direction. Such a shaft member 12a can be manufactured by, for example, rolling. Such a shaft member 12a is more suitable for use due to its high rigidity. The direction of the grain flows can be, for example, the axial direction or the circumferential direction.

[0069] In this embodiment, the shaft member 12a is made of low-carbon steel. The shaft member 12a is carburized and quenched. This increases the strength of the entire shaft member 12a. This increases the strength of the first raceway surface 33a and the strength of the strength retaining portion 34a.

[0070] In this embodiment, the follower bearing 11a includes a cage 15a that holds multiple rollers 14a. The cage 15a includes multiple column portions 45a that are arranged between the rollers 14a, and annular connecting portions 46a, 47a that are connected to one axial end of the column portions 45a and connect the multiple column portions 45a. Therefore, the cage 15a can appropriately guide the rolling of the rollers 14a while appropriately maintaining the circumferential spacing of the rollers 14a. This ensures smooth driving of the follower bearing 11a.

[0071] In this embodiment, both the follower bearing 11a and the mounting fixture 70a are provided with an anti-rotation mechanism 40a that prevents rotation of the components. Therefore, when fastening the follower bearing 11a and the mounting fixture 70a, the anti-rotation mechanism 40a can be used to prevent rotation of at least a portion of the components of either the follower bearing 11a or the mounting fixture 70a. Therefore, with this follower bearing module 10a, it is possible to reduce the installation space and improve convenience when mounting the follower bearing 11a.

[0072] In this embodiment, both the follower bearing 11a and the mounting fixture 70a are provided with an anti-slip mechanism 50a that prevents slippage of the rotating member. Therefore, when either the follower bearing 11a or the mounting fixture 70a is rotated to fasten the follower bearing 11a to the mounting fixture, slippage of the rotating member is prevented, and the rotating member can be rotated reliably. Therefore, with this follower bearing module 10a, it is possible to reduce the installation space and improve convenience when installing the follower bearing 11a.

[0073] In the above embodiment, the lubricant supply hole 24a includes the first hole 25a and the second hole 26a, but this is not limited thereto. For example, the lubricant supply hole 24a may be composed of a through hole that penetrates from the first end face 21a to the first track surface 33a in one direction, or may include multiple first holes 25a, or may include one first hole 25a and multiple second holes 26a.

[0074] Second Embodiment Next, a second embodiment, which is another embodiment, will be described. FIG. 11 is a schematic perspective view of a follower bearing module according to the second embodiment of the present disclosure. FIG. 12 is a schematic cross-sectional view taken along the line XII-XII in FIG. 11 . FIG. 12 is a cross-sectional view taken along a plane including a rotation axis 16b (described later) and parallel to the Y-Z plane. FIG. 13 is a schematic cross-sectional view taken along the line XIII-XIII in FIG. 11 . FIG. 13 is a cross-sectional view taken along a plane including a rotation axis 16b and parallel to the X-Y plane. FIG. 12 shows a cross-sectional view taken along a plane that does not include a bar portion included in a cage (described later), and FIG. 13 shows a cross-sectional view taken along a plane that includes a bar portion included in the cage. FIG. 14 is an exploded perspective view that schematically illustrates the follower bearing module shown in FIG. 11 . The attached member is not illustrated in FIG. 14 . FIG. 15 is a schematic perspective view that illustrates a portion of a follower bearing module according to the second embodiment. Specifically, Fig. 15 shows a state in which the outer ring included in the follower bearing has been removed from the follower bearing module in the state shown in Fig. 12 and Fig. 13. The follower bearing module in embodiment 2 basically has the same configuration as in embodiment 1 and achieves the same effects. However, the follower bearing module in embodiment 2 differs from embodiment 1 in that the follower bearing does not have a lubricant supply hole, for example.

[0075] 11 , 12 , 13 , 14 , and 15 , the follower bearing module 10b of the second embodiment includes a follower bearing 11b and a mounting fixture 70b. The follower bearing 11b includes a shaft member 12b as an inner member, an outer ring 13b, a plurality of rollers 14b as rolling elements, a cage 15b that holds the rollers 14b, and a side plate 19b that is a ring. Unlike the follower bearing 11a of the first embodiment, the follower bearing 11b does not include a refill plug or a pair of sealing members. In FIGS. 12 and 13 , the rotation axis 16b, which is the center axis of the shaft member 12b, is shown by a dashed line.

[0076] The shaft member 12b includes a main body portion 17b and a flange portion 18b having a diameter larger than that of the main body portion 17b. The main body portion 17b has a first end face 21b, which is one end in the axial direction, and a second end face 22b, which is the other end opposite the first end face 21b. The outer peripheral surface 23b of the annular flange portion 18b faces the outer ring 13b. The outer ring 13b has an annular second raceway surface 51b on its inner peripheral surface that faces the first raceway surface 33b. The outer ring 13b has an annular outer peripheral surface 52b, a first end face 53b, and a second end face 54b. The basic configuration of the outer ring 13b is similar to that of the outer ring 13a in embodiment 1, and therefore description thereof will be omitted.

[0077] The main body 17b includes a shaft portion 31b and a large-diameter portion 32b. A first raceway surface 33b having a cylindrical surface shape is formed on the outer peripheral surface of the large-diameter portion 32b. Unlike the shaft member 12a in the first embodiment, the shaft member 12b does not have a lubricant supply hole. The shaft member 12b has a recess 24b recessed from the first end face 21b. The opening of the recess 24b on the first end face 21b side is circular. The interior of the recess 24b has a hexagonal socket shape that allows a hexagonal wrench to be inserted and fitted into it. The hexagonal socket-shaped portion of the recess 24b functions as the rotation prevention mechanism 40b. The hexagonal socket-shaped portion of the recess 24b also functions as the slip prevention mechanism 50b.

[0078] The outer peripheral surface 37b of the shaft portion 31b is a cylindrical surface. Similar to the shaft portion 31a in the first embodiment, the shaft portion 31b is provided with a threaded hole 38b recessed in the axial direction. A thread groove 39b is formed in the threaded hole 38b of the shaft portion 31b. That is, the thread groove 39b is formed on the inner peripheral surface of the shaft portion 31b. The axial length of the region where the thread groove 39b is formed is length D ２ The axial length D of the region where the screw groove 39b is formed is ２ is 1.5 to 3 times the diameter of the thread of the body 71b of the mounting fixture 70b, which will be described later. ２ It is shown as follows.

[0079] The outer ring 13b has an annular shape. The outer ring 13b has an annular second raceway surface 51b on its inner circumferential surface that faces the first raceway surface 33b. The outer ring 13b also has an annular outer circumferential surface 52b, a first end face 53b, and a second end face 54b. In this embodiment, the outer circumferential surface 52b is cylindrical except for both axially chamfered ends. In the axial direction, the radial thickness of a central portion 55b of the outer ring 13b on which the second raceway surface 51b is provided is greater than the radial thickness of one end portion 56b including the first end face 53b and the radial thickness of the other end portion 57b including the second end face 54b.

[0080] The cage 15b has an annular shape. The cage 15b is disposed concentrically with the shaft member 12b and the outer ring 13b in the space between the shaft member 12b and the outer ring 13b. Unlike the cage 15a in the first embodiment, the cage 15b includes a plurality of column portions 45b disposed between the rollers 14b in the circumferential direction and a connecting portion 46b connecting the column portions 45b. That is, the cage 15b in the second embodiment differs from the cage 15a in the first embodiment in that only one connecting portion 46b is provided. The connecting portion 46b is annular and is provided at one axial end of the column portions 45b. The cage 15b has a plurality of pockets 48b disposed at equal intervals in the circumferential direction. The rollers 14b are disposed on an annular orbit along the first raceway surface 33b and the second raceway surface 51b so as to contact the first raceway surface 33b and the second raceway surface 51b. Roller 14b includes a cylindrical outer peripheral surface 58b and a pair of flat end surfaces 59b, 60b. Roller 14b contacts first raceway surface 33b and second raceway surface 51b at outer peripheral surface 58b. One axial end surface 59b of roller 14b contacts and is guided by connecting portion 46b. The basic configuration of roller 14b is the same as that of roller 14a in embodiment 1, so a description thereof will be omitted.

[0081] Similar to the side plate 19a in the first embodiment, the side plate 19b is coaxially disposed on the main body portion 17b so as to circumferentially surround a portion of the outer peripheral surface of the main body portion 17b. The annular side plate 19b has a first end face 41b, which is one end face, a second end face 42b, which is the other end face, an outer peripheral surface 43b, and an inner peripheral surface 44b. The side plate 19b is positioned so that the first end face 41b contacts the stepped surface 36b, which is the end face of the large diameter portion 32b on the shaft portion 31b side. The basic configuration of the side plate 19b is similar to that of the side plate 19a in the first embodiment, and therefore a description thereof will be omitted. Because the cage 15b described above does not have a connecting portion on one axial side, the other axial end face 60b of the roller 14b contacts and is guided by the first end face 41b of the side plate 19b.

[0082] Next, the configuration of the mounting fixture 70b included in the follower bearing module 10b of embodiment 2 will be described. Fig. 16 is a schematic perspective view of the mounting fixture 70b. Fig. 17 is a schematic rear view of the mounting fixture 70b. Fig. 17 is a view of the mounting fixture 70b viewed in the direction opposite to the arrow Y.

[0083] 16 and 17 , the mounting fixture 70b includes a body portion 71b and a head portion 72b. Similar to the body portion 71a in the first embodiment, the body portion 71b has a shape extending in the axial direction. A thread 74b is formed on an outer peripheral surface 73b of the body portion 71b. The body portion 71b is fitted into the thread groove 39b. Similar to the head portion 72a in the first embodiment, the head portion 72b is provided at one axial end of the body portion 71b. The head portion 72b has a shape extending toward the outer diameter side. In this embodiment, the head portion 72b is flat. The outer shape of the head portion 72b is circular when viewed in the axial direction (Y direction), which is the thickness direction of the head portion 72b. The head portion 72b includes a surface (first surface) 75b located on one side in the thickness direction (axial direction) and a surface (second surface) 76b located on the other side in the thickness direction. The body portion 71b is provided on the surface 76b side.

[0084] The head 72b includes a hole 77b as a rotation prevention mechanism 40b recessed from one surface in the thickness direction. That is, the hole 77b is recessed in the axial direction. The hole 77b has portions with different diameters. In this embodiment, the outer shape of the hole 77b is a hexagonal socket. A hexagonal wrench, which serves as a tool to prevent rotation of the mounting fixture 70b, can be fitted into the hole 77b from the axial direction. The hexagonal socket-shaped portion of the hole 77b functions as the rotation prevention mechanism 40b. The hexagonal socket-shaped portion of the hole 77b also functions as the anti-slip mechanism 50b.

[0085] Here, the configuration of the shaft member 12b will be further described. A strength retaining portion 34b that maintains the strength of the follower bearing 11b is provided between an end portion 35b located on the first raceway surface 33b side of the region of the threaded hole 38b where the thread groove 39b is formed and the axial end portion of the first raceway surface 33b. In this embodiment, the axial end portion of the first raceway surface 33b is the portion where the step surface 36b is located. The axial length of the strength retaining portion 34b is length B ２ That is, in the axial direction, the end portion 35b in which the screw groove 39b is formed does not reach the end portion of the first raceway surface 33b. ２ is 0.1 to 1 times the diameter of the shaft portion 31b. The diameter of the shaft portion 31b is the length U ２ It is shown as follows.

[0086] For the follower bearing module 10b in embodiment 2, similar to the follower bearing module 10a in embodiment 1, the member to be mounted 90a is sandwiched between the follower bearing 11b and the mounting fixture 70b, and the screw thread 74b is fitted into the screw groove 39b to mount the follower bearing 11b.

[0087] The follower bearing module 10b configured as described above also achieves a compact installation space, simple installation, and high load-bearing capacity. Furthermore, because the lubricant supply hole of the first embodiment is not provided, the rigidity of the shaft member 12b can be maintained at a high level, further improving load-bearing capacity, and reducing the number of processing steps, thereby improving productivity.

[0088] Third Embodiment Next, a third embodiment, which is another embodiment, will be described. FIG. 18 is a schematic perspective view of a follower bearing module according to the third embodiment of the present disclosure. FIG. 19 is a schematic cross-sectional view taken along the line indicated by XIX-XIX in FIG. 18. FIG. 19 is a cross-sectional view taken along a plane including the rotation axis 16a and parallel to the Y-Z plane. FIG. 20 is an exploded perspective view schematically showing the follower bearing module shown in FIG. 18. The attached member is not shown in FIG. 20. FIG. 21 is a schematic perspective view of a mounting fixture included in the follower bearing module according to the third embodiment. FIG. 22 is a schematic rear view of the mounting fixture shown in FIG. 21. FIG. 22 is a view of the mounting fixture viewed from the direction opposite to the arrow Y. The follower bearing module according to the third embodiment basically has the same configuration as that of the first embodiment and achieves the same effects. However, the configuration of the mounting fixture of the follower bearing module according to the third embodiment is different from that of the first embodiment.

[0089] 18 to 22, the follower bearing module 10c according to the third embodiment includes a follower bearing 11a and a mounting fixture 70c. The follower bearing module 10c is a follower bearing module in which the follower bearing 11a is mounted to a mounting member 90a having a mounting hole 93a. The follower bearing 11a included in the follower bearing module 10c is basically the same in configuration as the follower bearing 11a included in the follower bearing module 10a according to the first embodiment, except that the opening area of ​​the screw hole 38a is larger and the depth of the screw hole 38a is deeper, and therefore a description thereof will be omitted.

[0090] The mounting fixture 70c includes a body portion 71c and a head portion 72c. The body portion 71c has a shape extending in the axial direction. A screw thread 74c is formed on an outer peripheral surface 73c of the body portion 71c. The body portion 71c is fitted into the screw groove 39a. The head portion 72c is provided at one axial end of the body portion 71c. The head portion 72c has a shape extending toward the outer diameter side. In this embodiment, the head portion 72c is flat. Unlike the head portion 72a in Embodiment 1, the head portion 72c does not have a hexagonal hole formed therein. In other words, the head portion 72c does not have any holes or irregularities. The head portion 72c includes a surface (first surface) 75c located on one side in the thickness direction (axial direction) and a surface (second surface) 76c located on the other side in the thickness direction. The body portion 71c is provided on the surface 76c side. That is, a surface 75c of the head 72c in the axial direction, on which the body 71c is not provided, is configured as a flat surface.

[0091] The outer shape of the head 72c is polygonal when viewed in the axial direction (Y direction), which is the thickness direction of the head 72c. Specifically, it is hexagonal when viewed in the axial direction, which is the thickness direction of the head 72c (see FIG. 22 in particular). In this embodiment, the outer peripheral surface 77c, which corresponds to the side surface of the head 72c, is composed of six flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c. The flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c are connected at six corners 89c. The three pairs of flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c, specifically the pair of flat surfaces 83c and 86c, the pair of flat surfaces 84c and 87c, and the pair of flat surfaces 85c and 88c, are arranged parallel to each other when viewed in the axial direction.

[0092] The head 72c having such a configuration has a length from the center 16c at a portion corresponding to the rotation shaft 16a when viewed from the axial direction, which is a third length L ３ and a first portion 81c having a length from the center 16c of a third length L ３ A fourth length L that is longer than ４ and a second portion 82c having a length L ３ is the shortest length on the surface 75c from the center 16c to the end of the head 72c in the XZ plane, and the length L ４is the longest distance on surface 75c from center 16c to the end of head 72c in the X-Z plane. Of the six flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c that make up outer peripheral surface 77c, a pair of parallel flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c is fitted with a tightening tool, such as a wrench with an open tip, used to rotate mounting fixture 70c. With this configuration, compared to the first embodiment described above, it is easier to select the parallel flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c to fit the wrench into. In other words, it is possible to select the flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c that are easy to fit into depending on the rotation angle, making installation easier. That is, the flat surfaces 83c, 84c, 85c, 86c, 87c, and 88c function as a rotation prevention mechanism 40c that prevents rotation of the mounting fixture 70c and an anti-slip mechanism 50c that prevents slippage when the mounting fixture 70c is rotated.

[0093] That is, the follower bearing module 10c in the above-described third embodiment is a follower bearing module 10c in which a follower bearing 11a is attached to a mounted member 90a having a mounting hole 93a. The follower bearing module 10c includes a follower bearing 11a and a mounting fixture 70c that mounts the follower bearing 11a to the mounted member 90a. The follower bearing 11a includes an inner member having an annular first raceway surface 33a on its outer peripheral surface 23a, an outer ring 13a having an annular second raceway surface 51a on its inner peripheral surface 44a that faces the first raceway surface 33a, and rollers 14a as a plurality of rolling elements that are arranged on an annular orbit that follows the first raceway surface 33a and the second raceway surface 51a so as to come into contact with the first raceway surface 33a and the second raceway surface 51a. The inner member includes a large-diameter portion 32a provided with a first raceway surface 33a, and a shaft portion 31a extending axially from the large-diameter portion 32a and at least a portion of which is received within the mounting hole 93a. The shaft portion 31a is provided with a threaded hole 38a that is recessed in the axial direction and has a thread groove 39a formed on its inner peripheral surface. The mounting fixture 70c includes a body portion 71c extending axially, having a thread 74c formed on its outer peripheral surface 73c, and being fitted into the threaded hole 38a, and a head portion 72c provided at one axial end of the body portion 71c and extending radially outward. The outer shape of the head portion 72c is polygonal when viewed axially.

[0094] This follower bearing module 10c is comprised of a follower bearing 11a and a mounting fixture 70c, allowing for simple installation. Furthermore, the mounting fixture 70c and the follower bearing 11a can be fastened together by engaging the threads 74c formed on the body 71c of the mounting fixture 70c with the threaded hole 38a formed in the shaft portion 31a of the inner member, thereby attaching the follower bearing 11a to the mounting member 90a. In this case, the mounting fixture 70c can be attached by sandwiching the mounting member 90a between the head 72c of the mounting fixture 70c and the follower bearing 11a. Therefore, when installing the mounting fixture 70c, the axial length only requires a space approximately equal to the thickness of the head 72c, allowing for more compact installation space than fastening using a nut or the like. Furthermore, because the outer shape of the head 72c is polygonal when viewed in the axial direction, the head 72c can function as at least one of the anti-rotation mechanism 40c and the anti-slip mechanism 50c. Therefore, the installation can be made easier.

[0095] In this embodiment, the head 72c has a hexagonal outer shape, which allows the head 72c to be more appropriately fitted using a hexagonal wrench with an open tip, making it easier to function as at least one of the anti-rotation mechanism 40c and the anti-slip mechanism 50c.

[0096] In this embodiment, the surface 75c of the head 72c in the axial direction, where the body 71c is not provided, may be configured as a flat surface. This follower bearing module 10c can suppress a decrease in the strength of the mounting fixture 70c. Therefore, the strength of the follower bearing module 10c itself can be improved.

[0097] Fourth Embodiment Next, a fourth embodiment, which is another embodiment, will be described. FIG. 23 is a schematic perspective view of a follower bearing module according to the fourth embodiment of the present disclosure. FIG. 24 is a schematic cross-sectional view taken along the line XXIV-XXIV in FIG. 23. FIG. 24 is a cross-sectional view taken along a plane including the rotation axis and parallel to the Y-Z plane. FIG. 25 is an exploded perspective view schematically showing the follower bearing module shown in FIG. 23. The attached member is not shown in FIG. 25. FIG. 26 is a schematic perspective view of a mounting fixture included in the follower bearing module according to the fourth embodiment. FIG. 27 is a schematic rear view of the mounting fixture shown in FIG. 26. FIG. 27 is a view of the mounting fixture viewed from the direction opposite to the arrow Y. The follower bearing module according to the fourth embodiment basically has the same configuration as that of the first embodiment and achieves the same effects. However, the follower bearing module according to the fourth embodiment differs from that according to the second embodiment in the configuration of the mounting fixture, etc.

[0098] 23 to 27 , the follower bearing module 10d according to the fourth embodiment includes a follower bearing 11b and a mounting fixture 70d. The follower bearing module 10d is a follower bearing module in which the follower bearing 11b is mounted to a mounting member 90a having a mounting hole 93a. The follower bearing 11b included in the follower bearing module 10d differs from the follower bearing 11b according to the second embodiment in that it includes a pair of sealing members similar to the pair of sealing members 66a and 67a included in the follower bearing 11a according to the first embodiment. That is, the follower bearing 11b according to the fourth embodiment includes a pair of sealing members 66d and 67d disposed at both axial ends of the outer ring 13b. The sealing member 66d is mounted so as to contact the outer peripheral surface 23b of the flange 18b. The seal member 67d is attached so as to come into contact with the outer peripheral surface 43b of the side plate 19b. The pair of seal members 66d, 67d seal the interior of the follower bearing 11b. Furthermore, the follower bearing 11b has a larger opening area of ​​the threaded hole 38b and a deeper threaded hole 38b than the follower bearing 11b in embodiment 2. The rest of the configuration of the follower bearing 11b in embodiment 4 is basically the same as the configuration of the follower bearing 11b shown in embodiment 2, so a description thereof will be omitted.

[0099] The mounting fixture 70d includes a body 71d and a head 72d. The body 71d has a shape extending in the axial direction. A screw thread 74d is formed on an outer peripheral surface 73d of the body 71d. The body 71d is fitted into the screw groove 39b. The head 72d is provided at one axial end of the body 71d. The head 72d has a shape extending toward the outer diameter. In this embodiment, the head 72d is flat. Unlike the head 72b in Embodiment 2, the head 72d does not have a hexagonal hole. That is, the head 72d does not have any holes or irregularities. The head 72d includes a surface (first surface) 75d located on one side in the thickness direction (axial direction) and a surface (second surface) 76d located on the other side in the thickness direction. The body 71d is provided on the surface 76d side. That is, a surface 75d of the head 72d in the axial direction, on which the body 71d is not provided, is configured as a flat surface.

[0100] The outer shape of the head 72d is polygonal when viewed in the axial direction (Y direction), which is the thickness direction of the head 72d. Specifically, it is hexagonal when viewed in the axial direction, which is the thickness direction of the head 72d (see FIG. 22 in particular). In this embodiment, the outer peripheral surface 77d, which corresponds to the side surface of the head 72d, is composed of six flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d. The flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d are connected at six corners 89d. The three pairs of flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d, specifically, the pair of flat surfaces 83d and 86d, the pair of flat surfaces 84d and 87d, and the pair of flat surfaces 85d and 88d, are arranged so as to be parallel to each other when viewed in the axial direction.

[0101] The head 72d having such a configuration has a fifth length L from the center 16d at a portion corresponding to the rotation axis 16b when viewed from the axial direction. ５ and a first portion 81d having a length from the center 16d of a fifth length L ５ A sixth length L that is longer than ６ and a second portion 82d having a length L ５ is the shortest length on the surface 75d from the center 16d to the end of the head 72d in the XZ plane, and the length L ６is the longest distance on surface 75d from center 16d to the end of head 72d in the X-Z plane. Of the six flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d that make up outer peripheral surface 77d, a pair of parallel flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d is fitted with a tightening tool, such as a wrench with an open tip, used to rotate mounting fixture 70d. This configuration makes it easier to select the parallel flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d to fit the wrench, compared to the second embodiment described above. This makes it possible to select the flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d that are easy to fit into depending on the rotation angle, making installation easier. That is, the flat surfaces 83d, 84d, 85d, 86d, 87d, and 88d function as a rotation prevention mechanism 40d that prevents rotation of the mounting fixture 70d and an anti-slip mechanism 50d that prevents slippage when the mounting fixture 70d is rotated.

[0102] Even with this configuration, it is possible to obtain the same effects as those in the third embodiment described above.

[0103] Other Embodiments In the above embodiment, rollers are used as the rolling elements, but this is not limiting, and balls may be used as the rolling elements. By doing so, the size of the follower bearing, and therefore the follower bearing module, can be made compact.

[0104] Furthermore, in the above embodiment, the shaft member, which is the inner member, is constructed as a single unit, but this is not limited to this, and the shaft member, which is the inner member, may be constructed by assembling multiple members.

[0105] In the above-described embodiment, the material of the shaft member, which is the inner member, may be stainless steel. The shaft member may be vacuum quenched. This increases the strength of the shaft member while providing a follower bearing module with excellent corrosion resistance.

[0106] Furthermore, in the above embodiment, the external shape of the head of the attachment is hexagonal, but the external shape of the head may be rectangular, pentagonal, octagonal, or decagonal. That is, the external shape of the head may be polygonal. Specifically, the external shape of the head may be composed of a plurality of flat surfaces. Furthermore, in the external shape of the head, the corners where the flat surfaces join may be rounded. That is, the corners where the flat surfaces join may be chamfered, such as by C-chamfering or R-chamfering. That is, the external shape of the head may have portions with different lengths from the center to the ends.

[0107] The present invention is intended to cover a wide range of applications, including those related to the present invention, including those related to the present invention.

[0108] 10a, 10b, 10c, 10d Follower bearing module, 11a, 11b Follower bearing, 12a, 12b Shaft member, 13a, 13b Outer ring, 14a, 14b Roller, 15a, 15b Cage, 16a, 16b Rotating shaft, 16c, 16d Center, 17a, 17b Main body, 18a, 18b Flange, 19a, 19b Side plate, 21a, 21b, 41a, 41b, 53a, 53b First end surface, 22a, 22b, 42a, 42b, 54a, 54b Second end surface, 23a, 23b, 37a, 37b, 43a, 43b, 52a, 52b, 58a, 58b, 73a, 73b, 73c, 73d, 77c, 77d, 83a, 84a Outer surface, 24a Lubricant supply hole, 24b Recess, 25a First hole, 26a Second hole, 27a First region, 28a Second region, 29a Third region, 31a, 31b Shaft portion, 32a, 32b Large diameter portion, 33a, 33b First raceway surface, 34a, 34b Strength retaining portion, 36a, 36b Step surface, 38a, 38b Screw hole, 39a, 39b Screw groove, 40a, 40b, 40c, 40d Anti-rotation mechanism, 44a, 44b Inner peripheral surface, 45a, 45b; Column portion, 46a, 46b, 47a; Connection portion, 48a, 48b; Pocket, 50a, 50b, 50c, 50d; Anti-slip mechanism, 51a, 51b; Second raceway surface, 55a, 55b; Center portion, 35a, 35b, 56a, 56b, 57a, 57b; End portion, 59a, 59b, 60a, 60b; End face, 61a; Refill plug, 62a; Guide hole, 63a; Injection hole, 64a; Discharge hole, 66a, 66d, 67a, 67d; Seal member, 70a, 70b, 70c, 70d; Mounting fixture, 71a, 71b, 71c, 71d; Body portion, 72a, 72b, 72c, 72d Head, 74a, 74b, 74c, 74d; Thread, 75a, 75b, 75c, 75d; Surface (first surface), 76a, 76b, 76c, 76d; Surface (second surface), 77b, 85a; Hole, 81a, 81c, 81d; First portion, 82a, 82c, 82d; Second portion, 83c, 83d, 84c, 84d, 85c, 85d, 86c, 86d, 87c, 87d, 88c, 88d; Flat surface, 89c, 89d; Corner, 90a, 90b; Attached member, 91a, 91b; First surface, 92a, 92b; Second surface, 93a, 93b; Attaching hole, 94a, 94b; Inner wall surface.

Claims

1. A follower bearing module for mounting a follower bearing to a mounted member having a mounting hole, comprising: a follower bearing; and a mounting fixture for mounting the follower bearing to the mounted member, wherein the follower bearing comprises: an inner member having an annular first raceway surface on its outer peripheral surface; an outer ring having an annular second raceway surface on its inner peripheral surface that faces the first raceway surface; and a plurality of rolling elements arranged on annular tracks along the first and second raceway surfaces so as to contact the first and second raceway surfaces, the inner member comprising: a large diameter section provided with the first raceway surface; and a shaft section extending axially from the large diameter section and at least a portion of which is housed within the mounting hole, the shaft section being provided with a threaded hole that is recessed axially and has a thread formed on its inner peripheral surface, and the mounting fixture comprises: a body section extending axially and having a screw thread formed on its outer peripheral surface that is fitted into the threaded hole, a head portion provided at one axial end of the body portion and extending radially outward, wherein a strength retaining portion that maintains strength of the follower bearing is provided between an end portion of the threaded hole that is located on the first raceway surface side of a region where the thread groove is formed and an axial end portion of the first raceway surface.

2. A follower bearing module as described in claim 1, wherein the inner member has a lubricant supply hole extending from the end opposite to the side on which the shaft portion is arranged in the axial direction to the first raceway surface.

3. A follower bearing module as set forth in claim 2, wherein the lubricant supply hole has an opening on the axial side opposite to the side on which the shaft portion is disposed and includes: a first hole recessed in the axial direction; and a second hole extending from the first hole toward the outer diameter side to reach the first raceway surface.

4. The follower bearing module according to claim 2, wherein a refill plug is disposed in said lubricant refill hole.

5. A follower bearing module according to claim 1 or 2, wherein the axial length of said strength retaining portion is between 0.1 and 1 times the diameter of said shaft portion.

6. A follower bearing module according to claim 1 or 2, wherein the axial length of the region in which the thread groove is provided is between 1.5 and 3 times the thread diameter of the body portion.

7. A follower bearing module according to claim 1 or claim 2, wherein the inner member is constructed as a single unit.

8. A follower bearing module according to claim 1 or 2, wherein the grain flows of the inner member are aligned in the same direction.

9. A follower bearing module according to claim 1 or claim 2, wherein the inner member is made of low carbon steel and has been carburized and quenched.

10. A follower bearing module according to claim 1 or claim 2, wherein the inner member is made of stainless steel and has been subjected to vacuum quenching.

11. A follower bearing module as described in claim 1 or claim 2, wherein the follower bearing further includes a retainer that holds the plurality of rolling elements, the retainer including: a plurality of pillar portions arranged between the rolling elements; and an annular connecting portion connected to one axial end of the pillar portions and connecting the plurality of pillar portions.

12. A follower bearing module according to claim 1 or 2, wherein at least one of the follower bearing and the mounting fixture is provided with an anti-rotation mechanism for preventing rotation of the member.

13. A follower bearing module according to claim 1 or 2, wherein at least one of the follower bearing and the mounting fixture is provided with an anti-slip mechanism for preventing slippage of the rotating member.

14. A follower bearing module according to claim 1 or 2, wherein the outer shape of the head is polygonal when viewed in the axial direction.

15. The follower bearing module according to claim 14, wherein the outer shape of the head is hexagonal when viewed in the axial direction.

16. A follower bearing module for mounting a follower bearing to a mounted member having a mounting hole, comprising: a follower bearing; and a mounting fixture for mounting the follower bearing to the mounted member, wherein the follower bearing comprises: an inner member having an annular first raceway surface on its outer peripheral surface; an outer ring having an annular second raceway surface on its inner peripheral surface that faces the first raceway surface; and a plurality of rolling elements arranged on annular tracks along the first and second raceway surfaces so as to contact the first and second raceway surfaces, the inner member comprising: a large diameter portion provided with the first raceway surface; and a shaft portion extending axially from the large diameter portion and at least a portion of which is housed within the mounting hole, the shaft portion being provided with a threaded hole that is recessed axially and has a thread formed on its inner peripheral surface, and the mounting fixture comprises: a body portion extending axially, having a screw thread formed on its outer peripheral surface, and being fitted into the threaded hole, a head portion provided at one axial end of the body portion and extending radially outward, wherein the outer shape of the head portion is polygonal when viewed in the axial direction.

17. The follower bearing module according to claim 16, wherein the outer shape of the head is hexagonal.

18. A follower bearing module according to claim 16 or 17, wherein the surface of the head in the axial direction that is not provided with the body portion is configured as a flat surface.

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