Bearing device

Abstract

To secure the flexibility of a housing, in a bearing device in which a bearing for supporting a shaft-shaped tool is arranged in the housing.SOLUTION: A bearing device 10 comprises a plurality of bearings 20, an outer cylinder 31, and a housing 30 having an inner cylinder 32 constituted of a plurality of inner cylinder members 40. The inner cylinder members 40 include a first inner cylinder member 41, a plurality of second inner cylinder members 42 and a third inner cylinder member 43, and the second inner cylinder members 42 comprise an annular body part 42a, two first protrusions 42b and two second protrusions 42c. The first protrusions 42b are located between adjacent two first bottoms 42d which adjoin each other at first tips 42f in a circumferential direction, lengths of the first protrusions in the circumferential direction become short toward a first side from a second side in an axial direction, the second protrusions 42c are located between adjacent two second bottoms 42e which adjoin each other at second tips 42g in the circumferential direction, and lengths of the second protrusions in the circumferential direction become short toward the second side from the first side in the axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a bearing arrangement. [Background technology]

[0002] 2. Description of the Related Art A device having a blade that rotates around an axis (bone excavation cutter) is known as a device used in surgical operations for cutting bones and the like (see Patent Document 1).

[0003] The device disclosed in Patent Document 1 includes a tool having an axis (flexible shaft) and a blade attached to the tip of the axis, and a cylindrical housing (guide) that guides the tool. The device inserts the housing and tool into the body through an incision, and grinds the bone by accurately contacting the blade with the desired grinding position of the bone. For this reason, the axis and housing of the device are flexible and can be freely deformed by applying stress in a direction perpendicular to the axial direction. The device can rotate the tool around the axis while the tool and housing are bent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-029841 A Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Patent Document 1, in the device, a bearing is provided between the tool and the housing to realize smoother rotation of the tool. When a bearing is provided inside a cylindrical housing, a step must be provided as a portion for fixing the bearing to the inner circumference of the housing. However, when a step is provided, it is difficult to reduce the diameter of the housing used in the device, and it is difficult to reduce the wall thickness of the tube. In addition, a method is conceivable in which a tube shorter than the housing is inserted inside the housing (as a double tube), a step is generated between the end of the tube and the housing, and this step is used as the step. However, when the housing is made into a double tube, the outer tube hinders the deformation of the inner tube, making it difficult to bend the housing.

[0006] An object of the present disclosure is to ensure flexibility of a housing in a bearing device in which a bearing for supporting a shaft-shaped tool is provided inside the housing. [Means for solving the problem]

[0007] The bearing device of the present disclosure comprises a plurality of bearings and a housing that accommodates the bearings, the housing comprising an outer tube having a cylindrical shape and an inner tube that is composed of a plurality of inner tube members also having a cylindrical shape and is arranged inside the outer tube, the outer tube and the inner tube are deformable against stress in a direction perpendicular to the axial direction that is the extension direction, the plurality of inner tube members include a first inner tube member, a plurality of second inner tube members, and a third inner tube member, the first inner tube member is arranged on a first axial side of the outer tube, and the third inner tube member is arranged on a second axial side of the outer tube, The plurality of second inner cylinder members are arranged between a second axial side of the first inner cylinder member and a first axial side of the third inner cylinder member such that an inner circumference of the inner cylinder is in communication from the first inner cylinder member to the third inner cylinder member, the plurality of bearings include a first bearing arranged on a first axial side inside the outer cylinder and a second bearing arranged on a second axial side inside the outer cylinder, an end face of the first inner cylinder member on the first axial side contacts a side face of the second axial side of the first bearing, and an end face of the first inner cylinder member on the second axial side contacts a side face of the first bearing on the first axial side, the end face of the third inner cylinder member contacts a side surface of the second bearing on the first axial side, the end face of the third inner cylinder member on the first axial side contacts an end face of the second axial side of the second inner cylinder member located closest to the second axial side, the end face of the second inner cylinder member on the first axial side contacts an end face of the second axial side of the second inner cylinder member located closest to the second axial side, the end face of the second inner cylinder member on the first axial side contacts an end face of the second axial side of the first inner cylinder member or an end face of the second side of another second inner cylinder member adjacent on the first axial side, The end face contacts an end face of a first axial side of the third inner tube member or an end face of a first side of another adjacent second inner tube member on a second axial side, a side surface of the first axial side of the first bearing is fixed to a first axial side of the outer tube, and a side surface of the second axial side of the second bearing is fixed to a second axial side of the outer tube, the second inner tube member comprises an annular body portion, two first protrusions provided on the first axial side of the annular body portion, and two second protrusions provided on the second axial side of the annular body portion, and the first protrusions and the second protrusions areThe first protrusions are arranged at equal intervals in the circumferential direction, a first bottom is between adjacent first protrusions, a tip of the first protrusion is a first tip, a second bottom is between adjacent second protrusions, a tip of the second protrusion is a second tip, the first bottom does not overlap with the second bottom and the second tip in the axial direction, the first tip does not overlap with the second bottom and the second tip in the axial direction, the first protrusion is located between two adjacent first bottoms in the circumferential direction, the circumferential length becomes smaller from the second side in the axial direction to the first side, and the second protrusion is located between two adjacent second bottoms in the circumferential direction, the circumferential length becomes smaller from the first side in the axial direction to the second side. Effect of the Invention

[0008] According to the bearing device of the present disclosure, it is possible to provide a bearing that supports a shaft-shaped tool inside the housing while ensuring the flexibility of the housing. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a bearing device according to the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing a tool to be supported by the bearing device of the present disclosure. [Diagram 3] FIG. 3 is a schematic diagram showing the inner cylinder. [Figure 4A] FIG. 4A is a schematic diagram showing a first inner cylinder member. [Figure 4B] FIG. 4B is a schematic diagram showing the second inner cylinder member. [Figure 4C] FIG. 4C is a schematic diagram showing a third inner cylinder member. [Diagram 5] FIG. 5 is an explanatory diagram of the second inner cylinder member and a manufacturing method thereof. [Figure 6] FIG. 6 is an explanatory diagram of a state in which a tool is supported by the bearing device of the present disclosure and a state in which the bearing device is in use. [Figure 7] FIG. 7 is a cross-sectional view showing another embodiment of the bearing device of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Overview of the embodiments of the present disclosure> Below, an overview of the embodiments of the present disclosure will be listed and described.

[0011] (1) The bearing device of the present disclosure includes a plurality of bearings and a housing that accommodates the bearings. The housing includes an outer cylinder having a cylindrical shape, and an inner cylinder that is configured by a plurality of inner cylinder members having a cylindrical shape and is disposed inside the outer cylinder. The outer cylinder and the inner cylinder are deformable against stress in a direction perpendicular to the axial direction, which is the extension direction. The plurality of inner cylinder members include a first inner cylinder member, a plurality of second inner cylinder members, and a third inner cylinder member. The first inner cylinder member is disposed on a first axial side of the outer cylinder. The third inner cylinder member is disposed on a second axial side of the outer cylinder. The plurality of second inner cylinder members are disposed between a second axial side of the first inner cylinder member and a first axial side of the third inner cylinder member such that the inner circumference of the inner cylinder is connected from the first inner cylinder member to the third inner cylinder member. The plurality of bearings include a first bearing disposed on a first axial side inside the outer cylinder and a second bearing disposed on a second axial side inside the outer cylinder. An end face of the first axial side of the first inner cylinder member contacts a side face of the second axial side of the first bearing, and an end face of the second axial side of the first inner cylinder member contacts an end face of the first axial side of the second inner cylinder member located on the most first axial side. An end face of the second axial side of the third inner cylinder member contacts a side face of the first axial side of the second bearing, and an end face of the first axial side of the third inner cylinder member contacts an end face of the second axial side of the second inner cylinder member located on the most second axial side. An end face of the first axial side of the second inner cylinder member contacts an end face of the second axial side of the first inner cylinder member or an end face of the second side of the other second inner cylinder member adjacent on the first axial side. The end face of the second axial side of the second inner cylinder member contacts the end face of the first axial side of the third inner cylinder member or the end face of the first side of another adjacent second inner cylinder member on the second axial side. The side face of the first axial side of the first bearing is fixed to the first axial side of the outer cylinder. The side face of the second axial side of the second bearing is fixed to the second axial side of the outer cylinder. The second inner cylinder member includes an annular body, two first protrusions provided on the first axial side of the annular body, and two second protrusions provided on the second axial side of the annular body.The first protrusions and the second protrusions are arranged at equal intervals in the circumferential direction, the space between adjacent first protrusions is a first bottom, the tip of the first protrusion is a first tip, the space between adjacent second protrusions is a second bottom, and the tip of the second protrusion is a second tip. The first bottom does not overlap with the second bottom and the second tip in the axial direction, and the first tip does not overlap with the second bottom and the second tip in the axial direction. The first protrusion has a first tip located between two adjacent first bottoms in the circumferential direction, and the circumferential length becomes smaller from the second side to the first side in the axial direction. The second protrusion has a second tip located between two adjacent second bottoms in the circumferential direction, and the circumferential length becomes smaller from the first side to the second side in the axial direction.

[0012] According to the bearing device having the above-described configuration, it is possible to provide a bearing for supporting a shaft-shaped tool inside the housing while ensuring flexibility of the housing.

[0013] (2) In the bearing device of the present disclosure, it is preferable that a first axial distance between the first tip and the first bottom is different from a second axial distance between the second tip and the second bottom. In the case of the above configuration, a gap can be secured between adjacent inner tube members, thereby ensuring flexibility of the inner tube. This also ensures flexibility of the housing.

[0014] <Details of the embodiment of the present disclosure> Hereinafter, an embodiment of the present disclosure will be described.

[0015] [Overall configuration of the bearing device according to the present disclosure] Fig. 1 is a schematic cross-sectional view showing a bearing device of the present disclosure. Fig. 2 is a schematic view showing a tool that is to be supported by the bearing device of the present disclosure. The bearing device 10 shown in Fig. 1 is one embodiment of the bearing device of the present disclosure. As shown in Fig. 1, the bearing device 10 includes a bearing 20 and a housing 30. The bearing device 10 rotatably supports a tool 50 shown in Fig. 2 by the cylindrical housing 30 and the bearing 20 arranged inside the housing 30.

[0016] The directions in this disclosure will be described. A central axis C is defined in the bearing device 10. The direction along the central axis C and the direction parallel to the central axis C are defined as the "axial direction", the direction perpendicular to the central axis C is defined as the "radial direction", and the direction along a circle centered on the central axis C is defined as the "circumferential direction". In the following description, one side in the axial direction, which is the extension direction of the housing 30, is referred to as the first side, and the other side in the axial direction is referred to as the second side. Note that the central axis C shown in FIG. 1 is a straight line, but the central axis C may be a straight line or a curved line.

[0017] [tool] FIG. 2 shows a tool 50 which is an object to be supported by the bearing device 10 (see FIG. 1). The tool 50 is a shaft-shaped tool for grinding an object (e.g., a bone). As shown in FIG. 2, the tool 50 includes a columnar or cylindrical shaft portion 51, a connection portion 52 provided on a first axial side of the shaft portion 51, and a blade 53 provided on a second axial side of the shaft portion 51. In the following description, the central axis of the tool 50 is referred to as a central axis C1. The tool 50 is rotatably supported by the bearing device 10 with the central axis C1 approximately coinciding with the central axis C.

[0018] The tool 50 is made of metal. The shaft portion 51 is flexible and can be deformed when stress is applied in a direction perpendicular to the axial direction. The central axis C1 of the tool 50 is straight or curved. The connection portion 52 is a portion to which a drive device (a drive device 60 described later, see FIG. 6) for driving the shaft-shaped tool 50 to rotate about its axis can be detached. The blade 53 is a grindstone-like portion having a larger diameter than the shaft portion 51 and abrasive grains (e.g., diamonds) fixed to the surface of a portion machined into a spherical tip.

[0019] [Bearings] 1, the bearing device 10 includes a plurality of bearings 20. The plurality of bearings 20 includes a first bearing 20 (hereinafter also referred to as a first bearing 21) disposed on a first axial side of the housing 30, and a second bearing 20 (hereinafter also referred to as a second bearing 22) disposed on a second axial side of the housing 30. Note that, hereinafter, when simply referred to as a "bearing 20," the bearing 20 is used to describe a configuration common to the first bearing 21 and the second bearing 22.

[0020] The bearing 20 of this embodiment includes an outer ring 25, an inner ring 26, and a plurality of rolling elements (balls) 27. The plurality of rolling elements 27 are disposed between the outer ring 25 and the inner ring 26. The bearing 20 is a rolling bearing. The central axis of the bearing 20 coincides with the central axis C of the bearing device 10. The inner ring 26 has an inner diameter that allows the shaft portion 51 of the tool 50 to be inserted therethrough. The bearing 20 rotatably supports the shaft portion 51 of the tool 50 inserted into the inner circumference of the inner ring 26. Note that the bearing 20 is not limited to a rolling bearing, and may be, for example, a plain bearing.

[0021] [housing] As shown in FIG. 1, the housing 30 includes an outer cylinder 31, an inner cylinder 32, a cylinder base member 33, and a cylinder tip member 34. The housing 30 has an approximately cylindrical space inside that communicates from the end of the first side in the axial direction to the end of the second side. The housing 30 rotatably supports a tool 50 (see FIG. 2) inserted into the space. In the following description, the center line of the housing 30 is referred to as a center line C2. The center line C2 of the housing 30 coincides with the center line C of the bearing device 10. In addition, the center lines of the outer cylinder 31 and the inner cylinder 32 that constitute the housing 30 coincide with the center line C2. For this reason, in the following description, the center lines of the outer cylinder 31 and the inner cylinder 32 are referred to as a center line C2.

[0022] [Outer cylinder, cylinder base part, and cylinder tip part] The outer cylinder 31 is made of a flexible tubular member made of resin. The outer cylinder 31 has a center line C2. The center line C2 of the outer cylinder 31 is a straight line or a curved line. In the following description, the direction of the center line C2 is also referred to as the axial direction. The outer cylinder 31 is deformable when stress is applied in a direction perpendicular to the axial direction. The outer cylinder 31 has an approximately cylindrical space inside that can accommodate the bearing 20 and the inner cylinder 32.

[0023] The barrel base member 33 is provided at the end of the outer tube 31 on the first side in the axial direction. The barrel base member 33 of this embodiment is made of resin and is fixed to the end of the outer tube 31 on the first side in the axial direction by a method such as bonding, crimping, or welding. The barrel base member 33 may be made of metal. The barrel base member 33 has a substantially cylindrical shape and has a through hole 33a penetrating in the axial direction. The through hole 33a forms a space into which a drive unit (drive unit 60 shown in FIG. 6) can be inserted from the first side in the axial direction. An end face 33b on the second side in the axial direction of the barrel base member 33 contacts a side face 21a on the first side in the axial direction of the first bearing 21. Specifically, the end face 33b contacts a side face on the first side in the axial direction of the outer ring 25 of the first bearing 21 (in other words, a side face 21a on the first side in the axial direction of the first bearing 21) and does not contact an inner ring 26 of the first bearing 21.

[0024] The tip member 34 is provided at the end of the outer tube 31 on the second side in the axial direction. The tip member 34 of this embodiment is made of resin and is fixed to the end of the outer tube 31 on the second side in the axial direction by a method such as bonding, crimping, or welding. The tip member 34 may be made of metal. The tip member 34 has a substantially cylindrical shape with a rounded tip side. The tip member 34 has a through hole 34a whose hole diameter increases from the first side to the second side in the axial direction. The end face 34b on the first side in the axial direction of the tip member 34 contacts the side face 22a on the second side in the axial direction of the second bearing 22. The tip member 34 further includes a recess 34c provided on the inner diameter side of the end face 34b. The end face 34b does not contact the inner ring 26 of the second bearing 22. The end face 34b contacts a side surface on the second axial direction side of the outer ring 25 of the second bearing 22 (in other words, a side surface 22a on the second axial direction side of the second bearing 22).

[0025] A side surface 21a on a first axial side of the first bearing 21 is fixed to a first axial side of the outer cylinder 31 via a cylinder base member 33. A side surface 22a on a second axial side of the second bearing 22 is fixed to a second axial side of the outer cylinder 31 via a cylinder tip member 34.

[0026] [Inner cylinder] FIG. 3 is a schematic diagram showing an inner cylinder. As shown in FIG. 3, the inner cylinder 32 is composed of a plurality of inner cylinder members 40. The inner cylinder 32 has a center line C2. The center line C2 of the inner cylinder 32 is a straight line or a curved line. In the following description, the direction of the center line C2 is also referred to as the axial direction. The inner cylinder member 40 is made of metal and has a substantially cylindrical shape. The inner cylinder member 40 may be made of resin, for example. The plurality of inner cylinder members 40 include a first inner cylinder member 41, a plurality of second inner cylinder members 42, and a third inner cylinder member 43. The first inner cylinder member 41, the second inner cylinder member 42, and the third inner cylinder member 43 each have a different shape.

[0027] FIG. 4A is a schematic diagram showing the first inner cylinder member 41. The first inner cylinder member 41 is disposed on the first side of the inner cylinder 32 in the axial direction (see FIG. 3). As shown in FIG. 4A, the first inner cylinder member 41 includes an annular body portion 41a and two protrusions 41b provided on the second side of the annular body portion 41a in the axial direction. The two protrusions 41b are disposed at equal intervals in the circumferential direction. The first inner cylinder member 41 further includes a bottom 41c formed between adjacent protrusions 41b and a tip 41d which is the tip of the protrusion 41b. The first inner cylinder member 41 further includes a flat circular end surface 41e at the end of the first side in the axial direction of the annular body portion 41a. The end surface of the first inner cylinder member 41 on the second side in the axial direction is referred to as an end surface 41f. The end surface 41f includes the tip 41d and the bottom 41c.

[0028] FIG. 4B is a schematic diagram showing the second inner cylinder member 42. The second inner cylinder member 42 is disposed between the first inner cylinder member 41 and the third inner cylinder member 43 of the inner cylinder 32 (see FIG. 3). As shown in FIG. 4B, the second inner cylinder member 42 includes an annular body portion 42a, two first protrusions 42b provided on a first side in the axial direction of the annular body portion 42a, and two second protrusions 42c provided on a second side in the axial direction of the annular body portion 42a. The first protrusions 42b and the second protrusions 42c are disposed at equal intervals in the circumferential direction. The second inner cylinder member 42 further includes a first bottom 42d formed between adjacent first protrusions 42b and a second bottom 42e formed between adjacent second protrusions 42c. The second inner cylinder member 42 further includes a first tip 42f which is the tip of the first protrusion 42b, and a second tip 42g which is the tip of the second protrusion 42c. The end face of the second inner cylinder member 42 on the first side in the axial direction is referred to as end face 42x, and the end face of the second inner cylinder member 42 on the second side in the axial direction is referred to as end face 42y. The end face 42x includes the first tip 42f and the first bottom 42d. The end face 42y includes the second tip 42g and the second bottom 42e.

[0029] In the second inner cylinder member 42, the first bottom 42d is provided at a position where it does not overlap with the second bottom 42e and the second tip 42g in the axial direction. In other words, the circumferential phase of the first bottom 42d is shifted from the circumferential phase of the second bottom 42e and the second tip 42g. In the second inner cylinder member 42, the first tip 42f is provided at a position where it does not overlap with the second bottom 42e and the second tip 42g in the axial direction. In other words, the circumferential phase of the first tip 42f is shifted from the circumferential phase of the second bottom 42e and the second tip 42g.

[0030] FIG. 4C is a schematic diagram showing the third inner cylinder member 43. The third inner cylinder member 43 is disposed on the inner cylinder 32 at the second side in the axial direction (see FIG. 3). As shown in FIG. 4C, the third inner cylinder member 43 includes an annular body portion 43a and two protrusions 43b provided on the first side in the axial direction of the annular body portion 43a. The two protrusions 43b are disposed at equal intervals in the circumferential direction. The third inner cylinder member 43 further includes a bottom 43c formed between adjacent protrusions 43b and a tip 43d which is the tip of the protrusion 43b. The third inner cylinder member 43 further includes a flat circular end surface 43e at the end of the annular body portion 43a on the second side in the axial direction. The end surface on the first side in the axial direction of the third inner cylinder member 43 is referred to as an end surface 43f. The end surface 43f includes the tip 43d and the bottom 43c.

[0031] [Regarding the manufacturing method of the inner cylinder member] Fig. 5 is an explanatory diagram of the second inner cylinder member and its manufacturing method. As shown in Fig. 5, the second inner cylinder member 42 (see Fig. 4B) is manufactured by cutting a metal plate material into a predetermined shape and bending the plate piece 80 cut into the predetermined shape into a cylindrical shape. The plate piece 80 is manufactured, for example, by punching the metal plate material with a press device.

[0032] 5 shows the plate piece 80. The plate piece 80 is in a generally rectangular shape having four sides, including a first side 80a, a second side 80b, a third side 80c, and a fourth side 80d. A reference direction X is defined for the plate piece 80. The reference direction X is a direction parallel to the axial direction (the direction of the center line C2) of the second inner tube member 42 obtained by bending the plate piece 80 into a cylindrical shape.

[0033] The "predetermined shape" will be described below. In the plate piece 80, a first side 80a and a second side 80b have a linear shape and are formed parallel to the reference direction X. The plate piece 80 is bent so that the first side 80a and the second side 80b butt against each other, and processed into a cylindrical shape.

[0034] A third side 80c on a first side in the reference direction X of the plate piece 80 has a first shape K1, and a fourth side 80d on a second side of the plate piece 80 has a second shape K2. In this embodiment, the first shape K1 and the second shape K2 are both "sine waves" whose amplitude direction is the reference direction X.

[0035] The first shape K1 and the second shape K2 are both parts of the "sine wave" in the range of 0 to 4π (0° to 720°), and each has four inflection points. The first distance (amplitude) A in the first shape K1 is different from the second distance (amplitude) B in the second shape K2. The first distance A of the second inner cylinder member 42 of this embodiment is larger than the second distance B of the second inner cylinder member 42 (A>B). The "sine wave" of the first shape K1 and the "sine wave" of the second shape K2 have the same period. The "sine wave" of the first shape K1 and the "sine wave" of the second shape K2 differ in phase by an angle θ. The angle θ is an angle larger than -90° and smaller than 90° (-90°<θ<90°). In this embodiment, the phase of the "sine wave" of the first shape K1 differs from the phase of the "sine wave" of the second shape K2 by θ=45°.

[0036] In this embodiment, the first shape K1 and the second shape K2 are illustrated as being "sine waves", but the shapes of the first shape K1 and the second shape K2 are not limited to this and may be, for example, a "triangular wave".

[0037] The two protrusions 83 formed at the end 81 on the first side become the two first protrusions 42b of the second inner tube member 42. The width of the protrusion 83 in the direction perpendicular to the reference direction X becomes the circumferential length of the first protrusion 42b. The length L1 in FIG. 6 represents the maximum value of the circumferential length of the first protrusion 42b. The width of the protrusion 83 becomes smaller toward the first side in the reference direction X. Therefore, the circumferential width of the first protrusion 42b becomes smaller toward the first side in the axial direction. In other words, the first protrusion 42b has a shape that tapers toward the first side in the axial direction. Note that the "tapered" shape in this description may be a shape in which the circumferential width becomes smaller without increasing toward the tip side, and may include a portion in which the circumferential width does not change toward the tip side.

[0038] Two vertices 85 on the first side of the first shape K1 become two first tips 42f of the second inner cylindrical member 42. Two vertices 86 on the second side of the first shape K1 become two first bottoms 42d of the second inner cylindrical member 42.

[0039] The two protrusions 84 formed at the end 82 on the second side become the two second protrusions 42c of the second inner tube member 42. The width of the protrusions 84 in a direction perpendicular to the reference direction X becomes the circumferential length of the second protrusions 42c. The length L2 shown in FIG. 6 represents the maximum value of the circumferential length of the second protrusions 42c. The width of the protrusions 84 becomes smaller toward the second side in the reference direction X. Therefore, the circumferential width of the second protrusions 42c becomes smaller toward the second side in the axial direction. In other words, the second protrusions 42c have a shape that tapers toward the second side in the axial direction.

[0040] Two vertices 87 on the second side of the second shape K2 become two second tips 42g of the second inner cylinder member 42. Two vertices 88 on the first side of the second shape K2 become two second bottoms 42e of the second inner cylinder member 42 obtained by bending the plate piece 80 into a cylindrical shape.

[0041] In the second inner cylinder member 42, the first tip 42f is located between two first bottoms 42d adjacent to each other in the circumferential direction. The first protrusion 42b has a circumferential length that decreases from the second side to the first side in the axial direction. The second tip 42g is located between two second bottoms 42e adjacent to each other in the circumferential direction. The second protrusion 42c has a circumferential length that decreases from the first side to the second side in the axial direction.

[0042] The second inner cylinder member 42 having such a configuration is assembled by inserting the first protrusion 42b into a valley portion formed between two second protrusions 42c and inserting the second protrusion 42c into a valley portion formed between two protrusions 41b, so that a plurality of the second inner cylinder members 42 are arranged in the axial direction. At this time, the first protrusion 42b contacts the end face 41f of the first inner cylinder member 41 or the second end face 42y of the second inner cylinder member 42. At this time, the second protrusion 42c contacts the end face 43f of the third inner cylinder member 43 or the first end face 42x of the second inner cylinder member 42.

[0043] The protrusion 41b (see FIG. 4A) of the first inner cylinder member 41 has the same shape and dimensions as the second protrusion 42c of the second inner cylinder member 42. The protrusion 43b (see FIG. 4C) of the third inner cylinder member 43 has the same shape and dimensions as the first protrusion 42b of the second inner cylinder member 42.

[0044] The first inner cylinder member 41 and the third inner cylinder member 43 can be manufactured in the same manner as the second inner cylinder member 42. The first inner cylinder member 41 is manufactured in the same manner as the second inner cylinder member 42, by forming the first shape K1 of the plate piece 80 into a linear shape perpendicular to the reference direction X and bending the plate piece 80 into a cylindrical shape. The third inner cylinder member 43 is manufactured in the same manner as the second inner cylinder member 42, by forming the second shape K2 of the plate piece 80 into a linear shape perpendicular to the reference direction X and bending the plate piece 80 into a cylindrical shape.

[0045] In the bearing device 10 of this embodiment, a first axial distance A between the first end 42f and the first bottom 42d is different from a second axial distance B between the second end 42g and the second bottom 42e. With this configuration, a gap can be secured between adjacent inner tube members 40 (second inner tube members 42), thereby ensuring flexibility of the inner tube 32. This also ensures flexibility of the housing 30. Note that, in the bearing device 10 of this embodiment, the first distance A and the second distance B may be the same.

[0046] [Overall structure of the inner cylinder] As shown in Fig. 3, a first inner cylinder member 41 is disposed on the first most side in the axial direction of the inner cylinder 32, a third inner cylinder member 43 is disposed on the second most side in the axial direction of the inner cylinder 32, and a plurality of second inner cylinder members 42 are disposed between the first inner cylinder member 41 and the third inner cylinder member 43 of the inner cylinder 32. The inner circumferences of the first inner cylinder member 41, the plurality of second inner cylinder members 42, and the third inner cylinder member 43 are in communication from the end on the first side to the end on the second side in the axial direction. The inner cylinder 32 has a substantially cylindrical space D inside into which a tool 50 (see Fig. 2) can be inserted.

[0047] As shown in FIG. 3 and FIG. 4A to FIG. 4C, the first protrusion 42b of the second inner cylinder member 42 of the inner cylinder 32 is inserted into the valley portion formed on the end face 41f of the first inner cylinder member 41 of the inner cylinder 32. The second protrusion 42c of the second inner cylinder member 42 of the inner cylinder 32 is inserted into the valley portion formed on the end face 43f of the third inner cylinder member 43 of the inner cylinder 32. The protrusion 41b of the first inner cylinder member 41 of the inner cylinder 32 or the second protrusion 42c of the second inner cylinder member 42 of the inner cylinder 32 is inserted into the valley portion formed on the end face 42x of the second inner cylinder member 42 of the inner cylinder 32. The protrusion 43b of the third inner cylinder member 43 of the inner cylinder 32 or the first protrusion 42b of the second inner cylinder member 42 of the inner cylinder 32 is inserted into the valley portion formed on the end face 42y of the second inner cylinder member 42 of the inner cylinder 32.

[0048] [Flexibility of the inner cylinder] In the two second cylindrical members 42 adjacent in the axial direction, the end face 42y of the second inner cylinder member 42 on the first side contacts the end face 42x of the second inner cylinder member 42 on the second side. At this time, the second inner cylinder member 42 on the second side is allowed to move (rotate) relative to the second inner cylinder member 42 on the first side in a first direction around an axis passing through two contact points where the two first protrusions 42b and the end face 42y contact each other as rotation fulcrums. Furthermore, the second inner cylinder member 42 on the second side is allowed to move (rotate) relative to the second inner cylinder member 42 on the first side in a second direction in which the first protrusion 42b and the end face 42y contact each other at one of the two contact points, and the first protrusion 42b moves away from the end face 42y at the other contact point. In this way, when two second cylindrical members 42 are aligned in the axial direction and combined, the second inner tube member 42 on the second side is allowed to undergo relative displacement (rotation) in at least two directions around the same axis with respect to the second inner tube member 42 on the first side.

[0049] The second inner cylinder member 42 adjacent to the second side in the axial direction of the second inner cylinder member 42 on the second side described above is similarly allowed to be displaced (rotated) relative to the second inner cylinder member 42 on the first side in at least two directions about the same axis. Here, when comparing two second inner cylinder members 42 adjacent in the axial direction, the phase around the axis (circumferential direction) differs by θ between the two directions about the same axis in which the second inner cylinder member 42 on the first side in the axial direction is displaceable relative to a certain second inner cylinder member 42 and the two directions about the same axis in which the second inner cylinder member 42 on the second side in the axial direction is displaceable relative to a certain second inner cylinder member 42 (θ in this embodiment is θ=45°). In other words, between two axially adjacent second inner tube members 42, the direction in which the second inner tube member 42 on the first side relative to a given second inner tube member 42 can rotate is different from the direction in which the second inner tube member 42 on the second side relative to a given second inner tube member 42 can rotate.

[0050] Similarly, the second inner cylinder member 42 is allowed to be displaced (rotated) relative to the adjacent first inner cylinder member 41 in at least two directions about the same axis relative to the first inner cylinder member 41. Similarly, the second inner cylinder member 42 is allowed to be displaced (rotated) relative to the adjacent third inner cylinder member 43 in at least two directions about the same axis relative to the third inner cylinder member 43.

[0051] Each second inner cylinder member 42 included in the inner cylinder 32 has at least flexibility in two directions about the same axis according to the phase of the respective second inner cylinder members 42. And, since the direction in which each second inner cylinder member 42 can be displaced in the radial direction is shifted according to the phase about the axis (circumferential direction), the inner cylinder 32 has at least flexibility in many (almost all) radial directions. Also, the inner cylinder 32 has gaps between adjacent inner cylinder members 40, and these gaps serve to allow displacement relative to the adjacent inner cylinder members 40. For this reason, the inner cylinder 32 has a configuration that is deformable when stress is applied in a direction perpendicular to the axial direction.

[0052] Even when the inner tube 32 having such a configuration is housed inside the outer tube 31 (i.e., when the outer tube 31 and the inner tube 32 form a double tube), deformation is not hindered by the outer tube 31. Therefore, even when the housing 30 is configured to include the outer tube 31 and the inner tube 32, the flexibility of the housing 30 can be ensured.

[0053] [Overall structure of the housing] 1, in the bearing device 10, an end face 41e on the first axial side of the first inner cylinder member 41 contacts a side face 21b (side face of the outer ring 25) on the second axial side of the first bearing 21, and an end face 41f on the second axial side of the first inner cylinder member 41 contacts an end face 42x on the first axial side of the second inner cylinder member 42 located closest to the first axial side. In the bearing device 10, an end face 43e on the second axial side of the third inner cylinder member 43 contacts a side face 22b (side face of the outer ring 25) on the first axial side of the second bearing 22, and an end face 43f on the first axial side of the third inner cylinder member 43 contacts an end face 42y on the second axial side of the second inner cylinder member 42 located closest to the second axial side.

[0054] An end face 42x on the first axial side of the second inner cylinder member 42 contacts an end face 41f on the second axial side of the first inner cylinder member 41, or an end face 42y on the second side of another adjacent second inner cylinder member 42 on the first axial side. An end face 42y on the second axial side of the second inner cylinder member 42 contacts an end face 43f on the first axial side of the third inner cylinder member 43, or an end face 42x on the first side of another adjacent second inner cylinder member 42 on the second axial side. A side surface 21a on a first axial side of the first bearing 21 is fixed to a first axial side of the outer cylinder 31, and a side surface 22a on a second axial side of the second bearing 22 is fixed to a second axial side of the outer cylinder 31.

[0055] [Tool support by bearing device] 6 is an explanatory diagram of a state in which a tool is supported by the bearing device of the present disclosure and a state in which the bearing device is in use. As shown in FIG. 6, the bearing device 10 rotatably supports a tool 50 by a plurality of bearings 20 and a housing 30.

[0056] The connection part 52 on the first axial side of the tool 50 is inserted from the second axial side (through hole 34a) of the housing 30. The tool 50 is inserted to a depth at which the connection part 52 is located at a predetermined position in the barrel base member 33. At this time, the shaft part 51 is supported at the first axial side by the first bearing 21, and at the second axial side by the second bearing 22. At this time, the blade 53 is located outside the second axial side of the housing 30.

[0057] 6, when stress is applied in a direction perpendicular to the center line C, the bearing device 10 and the tool 50 are deformed in response to the stress. In this manner, the bearing device 10 of the present disclosure has the flexibility of the housing 30 while providing the bearing 20 that supports the axial tool 50 inside the housing 30.

[0058] The connection portion 52 of the tool 50 is gripped by a gripping portion (collet chuck) 61 of the driving device 60. The tool 50 is rotationally driven by the torque of the driving device 60. The torque of the driving device 60 rotates the blade 53 outside the housing 30. When the tool 50 is supported using the bearing device 10 of the present disclosure, the tool 50 is smoothly rotated around its axis, and the housing 30 and the tool 50 are bent in the desired direction. This action allows the blade 53 to be accurately brought into contact with the desired grinding position of the bone, allowing the bone to be ground with high precision.

[0059] [Regarding another embodiment of the bearing device of the present disclosure] Fig. 7 is a cross-sectional view showing another embodiment of the bearing device of the present disclosure. The bearing device 10 illustrated in Fig. 1 includes two bearings 20 (a first bearing 21 and a second bearing 22), but the bearing device of the present disclosure may include three or more bearings.

[0060] Another embodiment of the bearing device 10 of the present disclosure is shown in Fig. 7. As shown in Fig. 7, the bearing device 10 according to the another embodiment further includes a third bearing 20 (hereinafter also referred to as a third bearing 23) and a fourth bearing 20 (hereinafter also referred to as a fourth bearing 24) in addition to the first bearing 21 and the second bearing 22. The third bearing 23 and the fourth bearing 24 of this embodiment are both the same bearings 20 as the first bearing 21 and the second bearing 22, and are rolling bearings (ball bearings). Note that the third bearing 23 and the fourth bearing 24 may be plain bearings.

[0061] 7 includes a first bearing 21 and a third bearing 23 on a first axial side of a housing 30. The third bearing 23 is disposed on a second axial side of the first bearing 21. In the bearing device 10 according to the other embodiment, an end face 41e on the first axial side of the first inner cylinder member 41 contacts a side face 23a (a side face of the outer ring 25) on the second axial side of the third bearing 23.

[0062] The bearing device 10 according to the alternative embodiment has a spring 28 and a ring 29 disposed between the first bearing 21 and the third bearing 23. In the bearing device 10 according to the alternative embodiment, the third bearing 23 is fixed at a position a predetermined distance away from the first bearing 21 by the spring 28 and the ring 29. In the bearing device 10 according to the alternative embodiment, the first side of the shaft portion 51 in the axial direction can be supported more smoothly by the first bearing 21 and the third bearing 23 than in the bearing device 10 according to the above-described embodiment. In the bearing device 10 according to the alternative embodiment, the spring 28 and the ring 29 are disposed in the portion between the first bearing 21 and the third bearing 23, thereby providing flexibility and rigidity to that portion of the housing 30. Note that the spring 28 and the ring 29 may be omitted in the bearing device 10 according to the alternative embodiment.

[0063] The bearing device 10 according to another embodiment includes a second bearing 22 and a fourth bearing 24 on a second axial side of the housing 30. The fourth bearing 24 is disposed on a first axial side of the second bearing 22. In the bearing device 10 according to another embodiment, an end face 43e on the second axial side of the third inner cylinder member 43 contacts a side face 24a (a side face of the outer ring 25) on the first axial side of the fourth bearing 24.

[0064] The bearing device 10 according to the other embodiment has a spring 28 and a ring 29 arranged between the second bearing 22 and the fourth bearing 24. In the bearing device 10 according to the other embodiment, the fourth bearing 24 is fixed at a position a predetermined distance away from the second bearing 22 by the spring 28 and the ring 29. In the bearing device 10 according to the other embodiment, the second side in the axial direction of the shaft portion 51 can be supported more smoothly by the second bearing 22 and the fourth bearing 24 than in the bearing device 10 according to the above embodiment. In the bearing device 10 according to the other embodiment, the spring 28 and the ring 29 are arranged in the portion between the second bearing 22 and the fourth bearing 24, thereby providing flexibility and rigidity to the portion of the housing 30. Note that the spring 28 and the ring 29 may be omitted in the bearing device 10 according to the other embodiment.

[0065] According to the bearing device 10 of this embodiment (see FIG. 7), the housing 30 of the bearing device 10, in which a total of four bearings 20 for supporting a shaft-shaped tool 50 are provided, has flexibility. When the tool 50 is supported using the bearing device 10 according to another embodiment (see FIG. 7), the tool 50 is rotated more smoothly by the total of four bearings 20, and the housing 30 and the tool 50 can be bent in a desired direction.

[0066] [Actions and Effects of the Present Embodiment] (1) The bearing device 10 of this embodiment includes a plurality of bearings 20 and a housing 30 that accommodates the bearings 20. The housing 30 includes an outer cylinder 31 having a cylindrical shape, and an inner cylinder 32 that is configured with a plurality of inner cylinder members 40 having a cylindrical shape and is disposed inside the outer cylinder 31. The outer cylinder 31 and the inner cylinder 32 are deformable against stress in a direction perpendicular to the axial direction, which is the extension direction. The plurality of inner cylinder members 40 include a first inner cylinder member 41, a plurality of second inner cylinder members 42, and a third inner cylinder member 43. The first inner cylinder member 41 is disposed on a first side in the axial direction of the outer cylinder 31. The third inner cylinder member 43 is disposed on a second side in the axial direction of the outer cylinder 31. The second inner cylinder members 42 are arranged between the second axial side of the first inner cylinder member 41 and the first axial side of the third inner cylinder member 43 so that the inner circumference of the inner cylinder 32 is connected from the first inner cylinder member 41 to the third inner cylinder member 43. The bearings 20 include a first bearing 21 arranged on the first axial side inside the outer cylinder 31 and a second bearing 22 arranged on the second axial side inside the outer cylinder. An end face 41e on the first axial side of the first inner cylinder member 41 contacts a side face 21b on the second axial side of the first bearing 21. An end face 41f on the second axial side of the first inner cylinder member 41 contacts an end face 42x on the first axial side of the second inner cylinder member 42 located closest to the first axial side. The end face 43e of the third inner cylinder member 43 on the second axial side contacts the side surface 22b of the second bearing 22 on the first axial side. The end face 43f of the third inner cylinder member 43 on the first axial side contacts the end face 42y of the second inner cylinder member 42 located closest to the second axial side. The end face 42x of the second inner cylinder member 42 on the first axial side contacts the end face 41f of the second axial side of the first inner cylinder member 41, or the end face 42y of the second inner cylinder member 42 adjacent on the first axial side. The end face 42y of the second inner cylinder member 42 on the second axial side contacts the end face 43f of the third inner cylinder member 43 on the first axial side, or the end face 42x of the first axial side of the other second inner cylinder member 42 adjacent on the second axial side. A side surface 21a on a first axial side of the first bearing 21 is fixed to a first axial side of the outer cylinder 31. A side surface 22a on a second axial side of the second bearing 22 is fixed to a second axial side of the outer cylinder 31.The second inner cylinder member 42 includes an annular body portion 42a, two first protrusions 42b provided on a first axial side of the annular body portion 42a, and two second protrusions 42c provided on a second axial side of the annular body portion 42a. The first protrusions 42b and the second protrusions 42c are arranged at equal intervals in the circumferential direction. Between adjacent first protrusions 42b is a first bottom 42d, the tip of the first protrusion 42b is a first tip 42f, between adjacent second protrusions 42c is a second bottom 42e, and the tip of the second protrusion 42c is a second tip 42g. The first bottom 42d does not overlap with the second bottom 42e and the second tip 42g in the axial direction, and the first tip 42f does not overlap with the second bottom 42e and the second tip 42g in the axial direction. The first protrusion 42b has a first tip 42f located between two adjacent first bases 42d in the circumferential direction, and the circumferential length decreases from the second side to the first side in the axial direction. The second protrusion 42c has a second tip 42g located between two adjacent second bases 42e in the circumferential direction, and the circumferential length decreases from the first side to the second side in the axial direction.

[0067] According to the bearing device 10 shown in this embodiment, the housing 30 of the bearing device 10 in which the bearing 20 supporting the shaft-shaped tool 50 is provided has flexibility.

[0068] (2) In the bearing device 10 of this embodiment, the first axial distance A between the first end 42f and the first bottom 42d is different from the second axial distance B between the second end 42g and the second bottom 42e. In the case of the above-mentioned configuration, a gap can be secured between the adjacent inner tube members 40, thereby providing flexibility to the inner tube 32. This also provides flexibility to the housing 30.

[0069] The above-described embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is defined by the claims, not the above-described embodiment, and includes all modifications within the scope equivalent to the configurations described in the claims. [Explanation of symbols]

[0070] 10 Bearing device 20 Bearings 21 First Bearing 21a (first side) 21b (second side) side 22 Second bearing 22a (second side) 22b (first side) side 30 Housing 31 Outer cylinder 32 Inner cylinder 40 Inner cylinder member 41 First inner cylinder member 41e (first side) end face 41f (second side) end face 42 Second inner cylinder member 42a Circular body 42b First protrusion 42c Second prong 42d First Bottom 42e Second Bottom 42f First 42g Second tip 42x (first side) end face 42y (second side) end face 43 Third inner cylinder member 43e (second side) end face 43f (first side) end face A First Distance B Second distance

Claims

1. The present invention includes a plurality of bearings and a housing that accommodates the bearings, The housing includes an outer cylinder having a cylindrical shape, and an inner cylinder configured with a plurality of inner cylinder members having a cylindrical shape and disposed inside the outer cylinder, The outer cylinder and the inner cylinder are deformable against stress in a direction perpendicular to an axial direction, which is an extension direction, the plurality of inner cylinder members includes a first inner cylinder member, a plurality of second inner cylinder members, and a third inner cylinder member; the first inner cylinder member is disposed on a first side in an axial direction of the outer cylinder, the third inner cylinder member is disposed on a second axial side of the outer cylinder, the plurality of second inner cylinder members are disposed between a second axial side of the first inner cylinder member and a first axial side of the third inner cylinder member such that an inner circumference of the inner cylinder is in communication with the first inner cylinder member through the third inner cylinder member; the plurality of bearings include a first bearing disposed on a first axial side inside the outer cylinder and a second bearing disposed on a second axial side inside the outer cylinder, an end face of the first inner cylindrical member on a first axial side contacts a side face of the first bearing on a second axial side, and an end face of the first inner cylindrical member on the second axial side contacts an end face of the second inner cylindrical member on the first axial side that is located closest to the first axial side; an end face of the third inner cylinder member on a second axial side contacts a side face of the second bearing on a first axial side, and an end face of the third inner cylinder member on the first axial side contacts an end face of the second inner cylinder member on the second axial side that is located closest to the second axial side; an end surface of the second inner cylindrical member on a first axial side contacts an end surface of the first inner cylindrical member on a second axial side, or an end surface of the second axial side of another second inner cylindrical member adjacent to the first axial side; an end surface of the second inner cylindrical member on the second axial side contacts an end surface of the first axial side of the third inner cylindrical member or an end surface of the first side of another second inner cylindrical member adjacent to the third inner cylindrical member on the second axial side; A side surface of a first side in an axial direction of the first bearing is fixed to a first side in an axial direction of the outer cylinder, a side surface of the second bearing on a second side in the axial direction is fixed to a second side of the outer cylinder in the axial direction; the second inner cylinder member includes an annular body portion, two first protrusions provided on a first axial side of the annular body portion, and two second protrusions provided on a second axial side of the annular body portion, the first protrusions and the second protrusions are arranged at equal intervals in a circumferential direction, A space between adjacent first protrusions is a first bottom, a tip of the first protrusion is a first tip, a space between adjacent second protrusions is a second bottom, and a tip of the second protrusion is a second tip, The first bottom does not overlap with the second bottom and the second tip in the axial direction, the first tip does not axially overlap the second base and the second tip; The first protrusion has a first tip located between two of the first bottoms adjacent to each other in the circumferential direction, and a circumferential length of the first protrusion becomes smaller from the second side toward the first side in the axial direction, A bearing device in which the second protrusion has a second tip located between two adjacent second bottoms in the circumferential direction, and a circumferential length that decreases from the first side to the second side in the axial direction.

2. The bearing assembly of claim 1 , wherein a first axial distance between the first tip and the first bottom is different from a second axial distance between the second tip and the second bottom.

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