JP7577627B2 - Casing - Google Patents

Description

The present invention relates to a casing that houses a wire for transmitting a driving force.

Conventionally, wire drive force transmission mechanisms in which a wire for transmitting drive force is inserted into a tube have been widely used in hand brakes, robot hands, etc.

Patent document 1 discloses a cable system that includes a cable for transmitting a tensile force, a flexible tube that houses the cable, and a housing that surrounds the flexible tube. The housing is made up of multiple foam parts arranged in parallel.

The foam part is cylindrical with a bore. One end face of the foam part is provided with a support surface having a convex spherical curvature. The other end face of the foam part is provided with a concave opening that matches the support surface. When one side of the foam part is screwed onto the other side of the adjacent foam part, the surface of the support surface slides against the surface of the opening, and the foam parts are rotatably connected to each other. This causes the bores of the foam parts to form a continuous passage, and the flexible tube is housed in the passage.

Patent Document 2, like Patent Document 1, discloses a tube that is constructed by sequentially connecting multiple cylindrical joint rings to each other.

U.S. Pat. No. 6,250,175 JP 2014-124475 A

In Patent Document 1, when the housing is bent, the foam parts rotate relative to the adjacent foam parts. This causes the ends of the foam parts to protrude into the bores of the adjacent foam parts, which may come into contact with flexible tubes or wires and cause deformation of the wires.

In view of the above background, the present invention aims to provide a casing that has multiple cylindrical bodies that receive wires that transmit driving force, and that is less susceptible to deformation of the wires.

In order to solve the above problem, one aspect of the present invention is a casing (2, 52, 60) having a plurality of cylindrical bodies (10a, 10b, 10c, 10d, 10e) arranged in a row to form a receiving hole (12) for receiving a wire (6) that transmits a driving force, in which of two adjacent cylindrical bodies, one of the cylindrical bodies (10a, 10c, 10d) is provided with an insertion portion (20) that reduces in diameter at an end adjacent to the other cylindrical body, and the other cylindrical body (10b, 10e) is provided with an insertion portion (20) that reduces in diameter at an end adjacent to the one cylindrical body. The inner hole (12a, 12c) is expanded to match the insertion portion, and an insertion receiving portion (30) is provided to receive the insertion portion so that the axis of one of the cylindrical bodies can tilt relative to the axis of the other cylindrical body. When the insertion portion is inserted into the insertion receiving portion and the axis (Y, Z) of the other cylindrical body tilts a predetermined angle (δ) relative to the axis (X, Z) of one of the cylindrical bodies, the inner circumferential surfaces (18S, 28S, 54S) on the tilting direction side of the two cylindrical bodies are continuous and located on the same arc (Ca) in a cross section including the two axes.

According to this aspect, in a casing having multiple cylindrical bodies, when the casing is bent and a cylindrical body tilts at a predetermined angle relative to an adjacent cylindrical body, the inner circumferential surfaces of the two cylindrical bodies in the tilting direction are continuous and positioned on the same arc. Therefore, when a cylindrical body tilts at a predetermined angle relative to an adjacent cylindrical body, the end of the cylindrical body is less likely to protrude into the receiving hole, and deformation of the wire can be prevented.

In the above aspect, the inserting portion and the inserted portion may be provided with a restricting mechanism (38) that restricts the axis of one of the cylindrical bodies from tilting by more than a predetermined angle relative to the axis of the other cylindrical body.

This aspect prevents the wire from being bent to fit the casing, resulting in the wire's curvature becoming too large and causing a load to be applied to the wire.

In the above aspect, the regulating mechanism includes an annular shoulder surface (26) centered on the axis (X, Z) provided at the base end of the insertion portion, and an annular protruding end surface (34) centered on the axis (Y, Z) provided at the protruding end of the inserted portion, and when the insertion portion is inserted into the inserted portion and the axis of one of the cylindrical bodies is tilted by the angle relative to the axis of the other cylindrical body, the annular shoulder surface abuts against the annular protruding end surface.

According to this aspect, the annular shoulder surface and the annular end surface come into contact with each other, thereby restricting the central axis of the adjacent cylindrical body from tilting to an angle greater than a predetermined angle relative to the central axis of the cylindrical body.

In the above aspect, the annular shoulder surface has the outer peripheral surface of a right circular truncated cone, the annular end surface has the inner peripheral surface of an inverted circular truncated cone, the sum of the angle (θ) between the annular shoulder surface and the axis and the angle (φ) between the annular end surface and the axis is greater than 180 degrees, and when one of the cylindrical bodies is tilted by the predetermined angle relative to the other cylindrical body, the annular shoulder surface and the annular end surface make line contact within a plane including the two axes.

This configuration allows for more precise regulation of the tilting of the first cylindrical body relative to the second cylindrical body than when the annular shoulder surface and the annular end surface are in point contact.

In the above embodiment, the outer periphery of the insertion portion is provided with a convex sliding surface (22) having a convex spherical shape, and the inner periphery of the inserted portion is provided with a concave sliding surface (32) having a concave spherical shape, and the convex sliding surface and the concave sliding surface preferably have complementary shapes that allow them to slide against each other.

According to this embodiment, the cylindrical bodies can be connected to each other so that they can rotate.

In the above aspect, the device includes a first cylindrical body (10a) having the insertion portion at both ends and a second cylindrical body (10b) having the inserted portion at both ends, and the first cylindrical body and the second cylindrical body are preferably arranged alternately.

According to this aspect, the casing can be constructed by combining two types of members, the first cylindrical body and the second cylindrical body.

In the above aspect, the wall surface (28S) defining the inner hole of the second cylindrical body may be raised toward the axis between the inserted portions.

According to this aspect, the wall surface that defines the inner hole of the second cylindrical body is raised toward the central axis line, so that when the casing is bent and the cylindrical body tilts at a predetermined angle relative to the adjacent cylindrical body, the inner circumferential surfaces of the two cylindrical bodies in the tilting direction can be made continuous along the same circular arc.

In one aspect of the present invention, in order to solve the above problem, the cylindrical body (10c) may have the insertion portion at one end and the inserted portion at the other end.

According to this aspect, the casing can be constructed simply by combining a single type of component.

FIG. 1A is a partial cross-sectional view showing a casing according to a first embodiment in a most bent state; FIG. 1B is a perspective view showing a state in which a first cylindrical body and a second cylindrical body are assembled; and FIG. 1C is an enlarged view of a portion surrounded by a two-dot chain line in FIG. 1A. FIG. 13A is a partial cross-sectional view showing a casing according to a second embodiment in a most bent state; FIG. 13B is a perspective view showing a state in which two third cylindrical bodies are combined; FIG. 1A is a perspective view showing a modified example of a casing according to the present invention; and FIG. 1B is a diagram showing an example of a robot hand provided with the casing.

The casing according to this embodiment will be described with reference to the drawings.

First Embodiment
1, a casing 2 according to this embodiment is a case that receives a wire driving force transmission body 4. The wire driving force transmission body 4 includes a metal wire 6 for transmitting driving force including a pushing force and a pulling force, and a flexible tube 8 through which the wire 6 is inserted. The wire driving force transmission body 4 is used, for example, to drive a hand brake of a bicycle or the fingertip of a robot.

As shown in FIG. 1(A), the casing 2 includes a plurality of cylindrical bodies 10. Each cylindrical body 10 is a cylindrical member extending along the central axis X, Y, and has an inner hole 12 (bore) which is a through hole. The cylindrical body 10 may be made of a metal such as stainless steel, or may be made of a resin material such as plastic.

The cylindrical bodies 10 are arranged in a row. The inner holes 12 of the cylindrical bodies 10 are connected to the inner holes 12 of the adjacent cylindrical bodies 10. The continuous inner holes 12 form a receiving hole 13 for receiving the wire 6, and the receiving hole 13 constitutes a passage T for receiving the wire 6. In this embodiment, the wire 6 and the tube 8, which are the wire driving force transmission body 4, are inserted into the receiving hole 13.

The cylindrical body 10 includes a first cylindrical body 10a and a second cylindrical body 10b. The first cylindrical body 10a and the second cylindrical body 10b are arranged so as to alternate with each other.

As shown in FIG. 1B, the first cylindrical body 10a has a cylindrical shape that is rotationally symmetric about the central axis X. The inner hole 12 (hereinafter, inner hole 12a) of the first cylindrical body 10a extends along the central axis X and penetrates the first cylindrical body 10a. Both ends of the first cylindrical body 10a in the direction of the central axis X are adjacent to the second cylindrical body 10b. As shown in FIG. 1A, the inner hole 12a of the first cylindrical body 10a is reduced in diameter as it approaches the approximate center in the direction of the central axis X. The inner peripheral surface 18S (wall surface defining the inner hole 12a) of the first cylindrical body 10a rises toward the central axis at the approximate center in the direction of the central axis X in a vertical cross-sectional view including the central axis X, and is curved to form an approximately arc shape.

As shown in FIG. 1B, the first cylindrical body 10a has an insertion portion 20 at each end. The outer surface of the insertion portion 20 is tapered outward in the direction of the central axis X at the outer end (free end) in the direction of the central axis X. The outer surface at the free end of the insertion portion 20 (hereinafter, the convex sliding surface 22) is convex spherical.

The inner end (base end) of the insertion section 20 in the direction of the central axis X is provided with a step 24, which is a portion that expands in diameter in a step-like manner toward the base end side. The step 24 faces the direction of the adjacent second cylindrical body 10b and has an annular shoulder surface 26 that faces generally toward the free end side in the direction of the central axis X. The annular shoulder surface 26 forms an annular shape centered on the central axis X.

As shown in FIG. 1(C), the annular shoulder surface 26 is inclined toward the base end in a direction away from the central axis X. In other words, the annular shoulder surface 26 is inclined in a direction away from the adjacent second cylindrical body 10b as it moves away from the central axis X. As a result, as shown in FIG. 1(B), the annular shoulder surface 26 forms the outer peripheral surface of a right circular truncated cone.

The second cylindrical body 10b has a cylindrical shape that is rotationally symmetric about the central axis Y. The inner hole 12 (hereinafter, inner hole 12b) of the second cylindrical body 10b extends along the central axis Y and penetrates the second cylindrical body 10b. Both ends of the second cylindrical body 10b in the direction of the central axis Y are adjacent to the first cylindrical body 10a. As shown in FIG. 1(A), the inner hole 12b becomes smaller in diameter as it approaches approximately the center in the direction of the central axis Y.

As shown in FIG. 1B, the second cylindrical body 10b has an insertion portion 30 at each end. The inner hole 12b expands in diameter toward the outside in the direction of the central axis Y at the outer end (free end) of the insertion portion 30 in the direction of the central axis Y so as to receive the insertion portion 20 in a tiltable manner. The inner hole 12b has a shape that matches the insertion portion 20. The surface that defines the free end side of the insertion portion 30 of the inner hole 12b (hereinafter, the concave sliding surface 32) has a concave spherical shape. The convex sliding surface 22 and the concave sliding surface 32 have complementary shapes that can slide against each other. As shown in FIG. 1A, the inner peripheral surface 28S (wall surface that defines the inner hole 12b) of the second cylindrical body 10b rises toward the central axis Y between the insertion portions 30 and is curved to form an approximately arc shape in a vertical cross section including the central axis Y.

The end of the inserted portion 30 is provided with an annular end surface 34 that faces toward the adjacent first cylindrical body 10a and generally toward the central axis Y. The annular end surface 34 forms a ring shape centered on the central axis Y.

As shown in FIG. 1C, the annular end surface 34 is inclined toward the end as it moves away from the central axis Y. In other words, the annular end surface 34 is inclined toward the adjacent first cylindrical body 10a as it moves away from the central axis Y. As a result, the annular end surface 34 forms the inner peripheral surface of an inverted truncated cone.

In this embodiment, the sum of the angle θ between the central axis X of the first cylindrical body 10a and the annular shoulder surface 26 and the angle φ between the central axis Y of the second cylindrical body 10b and the annular end surface 34 is greater than 180 degrees.

As shown in FIG. 1A, the first cylindrical body 10a and the second cylindrical body 10b are alternately arranged along the wire 6. As shown in FIG. 1B, the insertion portion 20 of the first cylindrical body 10a is inserted into the inserted portion 30 of the adjacent second cylindrical body 10b so that the convex sliding surface 22 and the concave sliding surface 32 are in contact with each other. Since the convex sliding surface 22 and the concave sliding surface 32 have complementary shapes and can slide against each other, the first cylindrical body 10a and the second cylindrical body 10b are connected to be rotatable about the center point P of the concave sliding surface 32 (see FIG. 1C). As a result, the insertion portion 20 and the inserted portion 30 form a ball joint 36. At this time, as shown in FIG. 1(A), the inner hole 12a of the first cylindrical body 10a and the inner hole 12b of the second cylindrical body 10b are connected to form a receiving hole 13 through which the wire 6 and tube 8 are inserted.

As shown in FIG. 1(A), when the central axis X of the first cylindrical body 10a and the central axis Y of the second cylindrical body 10b are aligned, the first cylindrical body 10a tilts at a predetermined angle (hereinafter referred to as the upper limit angle δ), as shown in FIG. 1(C), the annular shoulder surface 26 hits the annular end surface 34, and the tilt is restricted. That is, the annular shoulder surface 26 and the annular end surface 34 form a restricting mechanism 38 that restricts the tilt of the first cylindrical body 10a relative to the second cylindrical body 10b by a predetermined angle or more. That is, the inserting portion 20 and the inserted portion 30 are provided with a restricting mechanism 38 that restricts the tilt of the first cylindrical body 10a relative to the second cylindrical body 10b by an upper limit angle δ or more. FIG. 1(A) shows the casing 2 in its most bent state.

In this embodiment, the sum of the angle θ between the central axis X of the first cylindrical body 10a and the annular shoulder surface 26 and the angle φ between the central axis Y of the second cylindrical body 10b and the annular end surface 34 is greater than 180 degrees, and the difference between θ and φ is equal to the upper limit angle δ. As a result, when the first cylindrical body 10a tilts relative to the second cylindrical body 10b by the upper limit angle δ, as shown in FIG. 1(C), the annular shoulder surface 26 and the annular end surface 34 are in line contact within a plane including the central axes X and Y. Therefore, the tilting of the first cylindrical body 10a relative to the second cylindrical body 10b can be more accurately restricted than when the annular shoulder surface 26 and the annular end surface 34 are in point contact.

When the first cylindrical body 10a is tilted by the upper limit angle δ relative to the adjacent second cylindrical body 10b, as shown in FIG. 1A, the first cylindrical body 10a and the second cylindrical body 10b are arranged so as to be aligned along the circumference C. The inner circumferential surface 18S of the first cylindrical body 10a and the inner circumferential surface 28S of the second cylindrical body 10b are continuous on the tilting direction side of the first cylindrical body 10a (the center side of the circumference C) in a cross section including the two central axes X and Y. Furthermore, the inner circumferential surface 18S of the first cylindrical body 10a is raised toward the central axis X between the insertion portions 20, and the inner circumferential surface 28S of the second cylindrical body 10b is raised toward the central axis Y between the inserted portions 30. The inner circumferential surface 18S of the first cylindrical body 10a and the inner circumferential surface 28S of the second cylindrical body 10b are both located on the same arc Ca on the tilting direction side of the first cylindrical body 10a (the center side of the circumference C) in a vertical cross section including the two central axes X and Y.

Next, the effect of the casing 2 configured in this manner will be described. As shown in FIG. 1(A), when the first cylindrical bodies 10a are tilted at the upper limit angle relative to the adjacent second cylindrical bodies 10b, the casing 2 bends and the wire 6 housed in the casing 2 curves to form an arc.

When the first cylindrical body 10a is tilted at the upper limit angle δ relative to the adjacent second cylindrical body 10b, in a cross section including the two central axes X and Y, the inner circumferential surface 18S of the first cylindrical body 10a and the inner circumferential surface 28S of the second cylindrical body 10b are located on the same arc Ca on the tilt direction side of the first cylindrical body 10a (the center side of the circumference C). Therefore, the end of the first cylindrical body 10a and the end of the second cylindrical body 10b can be prevented from protruding into the receiving hole 13. This prevents the wire 6 from being deformed due to the end of the first cylindrical body 10a or the end of the second cylindrical body 10b coming into contact with the wire 6, making it less likely that the transmission of driving force in a robot or the like will be hindered.

A restriction mechanism 38 is provided between the insertion portion 20 and the inserted portion 30, so that the rotation angle of the first cylindrical body 10a relative to the second cylindrical body 10b is restricted so as not to exceed the upper limit angle δ. This prevents the radius of curvature of the wire 6 from becoming less than the radius of the circumference C. In other words, it prevents the curvature of the wire 6 from becoming too large. This prevents a load from being applied to the wire 6.

The casing 2 is constructed by combining two types of components, a first cylindrical body 10a and a second cylindrical body 10b. This makes the construction simple and easy to assemble.

<<Second embodiment>>
Similar to the first embodiment, the casing 52 according to the second embodiment is a case that receives the wire driving force transmission body 4. As shown in Fig. 2(A), the casing 52 differs from the first embodiment in that it is made up of a plurality of cylindrical bodies 10 (hereinafter, third cylindrical bodies 10c) having the same shape. The configuration of the wire driving force transmission body 4 is similar to that of the first embodiment.

As shown in FIG. 2(B), the third cylindrical body 10c has a cylindrical shape that is rotationally symmetric about the central axis Z. The third cylindrical body 10c has an inner hole 12c that extends along the central axis Z and penetrates therethrough. The third cylindrical body 10c has an insertion portion 20 similar to the first cylindrical body 10a of the first embodiment at one end, and an inserted portion 30 similar to the second cylindrical body 10b of the first embodiment at the other end. As shown in FIG. 2(A), the third cylindrical bodies 10c are arranged in a row so that the insertion portion 20 of each third cylindrical body 10c is adjacent to the inserted portion 30 of the adjacent third cylindrical body 10c.

As in the first embodiment, the insertion portion 20 is tapered toward the adjacent third cylindrical body 10c. As in the first embodiment, the insertion portion 20 has a convex spherical sliding surface 22 on the outer surface of the free end side.

As in the first embodiment, the inserted portion 30 has an inner hole 12c that expands in diameter toward the adjacent third cylindrical body 10c. As in the first embodiment, the inserted portion 30 has a concave sliding surface 32 that is a concave spherical surface on the inner circumferential surface on the free end side. The concave sliding surface 32 and the convex sliding surface 22 have complementary shapes that allow them to slide against each other. As shown in FIG. 2(A), the inner circumferential surface 54S of the third cylindrical body 10c (the wall surface that defines the inner hole 12c) is raised toward the central axis Z between the inserting portion 20 and the inserted portion 30.

As shown in FIG. 2B, the insertion portion 20 of the third cylindrical body 10c is inserted into the inserted portion 30 of the adjacent third cylindrical body 10c so that the convex sliding surface 22 and the concave sliding surface 32 are in contact with each other. Since the convex sliding surface 22 and the concave sliding surface 32 have complementary shapes and can slide against each other, the third cylindrical body 10c is connected to the adjacent third cylindrical body 10c so as to be rotatable about the center point P of the concave sliding surface 32. This allows the casing 52 to be bent, similar to the first embodiment.

As shown in FIG. 2(A), a step 24 is provided on the base end side of the insertion portion 20, as in the first embodiment. The step 24 has an annular shoulder surface 26 that faces the adjacent third cylindrical body 10c. The tip side of the inserted portion 30 is provided with an annular protruding end surface 34, as in the first embodiment. The annular protruding end surface 34 faces the adjacent third cylindrical body 10c and has an annular shape.

When the third cylindrical body 10c tilts by the upper limit angle δ from when the central axis Z of the third cylindrical body 10c and the central axis Z of the adjacent third cylindrical body 10c are aligned, the annular shoulder surface 26 hits the annular end surface 34, and the tilt is restricted. That is, as in the first embodiment, the annular shoulder surface 26 and the annular end surface 34 form a restriction mechanism 38 that restricts the tilt of the third cylindrical body 10c relative to the adjacent third cylindrical body 10c. At this time, the inner circumferential surfaces 54S of the third cylindrical body 10c are each located on the same arc Ca on the tilting direction side (the center side of the circumference C) in a cross section including the two central axes Z. Figure 2 (A) shows the casing 52 in its most bent state.

Next, the effect of the casing 52 configured in this manner will be described. As in the first embodiment, when each of the third cylindrical bodies 10c is tilted by the upper limit angle δ relative to the adjacent third cylindrical bodies 10c, the casing 52 bends, and the wire 6 housed in the casing 52 curves to form an arc.

When each third cylindrical body 10c is tilted by the upper limit angle δ relative to the adjacent third cylindrical body 10c, the inner circumferential surface 54S of each third cylindrical body 10c is located on the same arc Ca on the tilting direction side (the center side of the circumference C) in a cross section including the central axis Z. This prevents the end of the third cylindrical body 10c from protruding into the receiving hole 13. This prevents the wire 6 from being deformed due to the end of the third cylindrical body 10c coming into contact with the wire 6.

The casing 52 is constructed by combining the third cylindrical body 10c, which is a single type of component. This makes the construction simple and easy to assemble.

This concludes the explanation of the specific embodiment, but the present invention is not limited to the above embodiment or modified examples, and can be implemented in a wide variety of variations.

In the above embodiment, the casings 2 and 52 house the wire 6 and the tube 8 that receives the wire 6, but this is not limited to the embodiment. The casing 52 may house only the wire 6 that transmits the driving force.

In the above embodiment, the ball joint 36 is formed by the inserting portion 20 and the inserted portion 30, but this is not limited to the above embodiment. As shown in FIG. 3(A), the connection portion (joint) formed by the inserting portion 20 and the inserted portion 30 of the cylindrical body 10 that constitutes the casing 60 may be a hinge joint 62 that connects the cylindrical body 10 to be rotatable around a single axis V.

When the wire 6 is provided across two links, it is preferable that the joint formed by the inserting portion 20 and the inserted portion 30 matches the connection mode of the two links.

Figure 3 (B) shows an example of two links L1, L2 provided on a robot hand H. The links L1, L2 are connected via a hinge joint J so as to be rotatable around one axis W. A wire 6 (not shown) is provided so as to straddle the links L1, L2 while being housed in the casing 60. In this case, the inserting section 20 and the inserted section 30 may be configured with a hinge joint 62 that connects the cylindrical bodies 10d, 10e so as to be rotatable around an axis V parallel to the axis W. As a result, the displacement of the cylindrical bodies 10d, 10e relative to the adjacent cylindrical bodies 10d, 10e is restricted around the axis V parallel to the axis W, so that the bending deformation of the casing 60 is limited within one plane perpendicular to the axis W. Therefore, the casing 60 can be prevented from bending in a direction perpendicular to that plane (i.e., a direction perpendicular to the paper surface of Figure 3 (B)).

2: Casing 6 according to the first embodiment: Wire 10: Cylindrical body 10: Cylindrical body 10a: First cylindrical body 10b: Second cylindrical body 10c: Third cylindrical body 10d: Cylindrical body 10e: Cylindrical body 12: Inner hole 12a: Inner hole 12b: Inner hole 12c: Inner hole 13: Receiving hole 18S: Inner circumferential surface 20: Inserting portion 22: Convex sliding surface 26: Annular shoulder surface 28S: Inner circumferential surface 30: Inserted portion 32: Concave sliding surface 34: Annular protruding end surface 38: Restricting mechanism 52: Casing 54S according to the second embodiment: Inner circumferential surface 60: Casing Ca according to the modified example: Arc X: Central axis Y: Central axis Z: Central axis θ: Angle φ: Angle

Claims (5)

A casing including a plurality of cylindrical bodies arranged in a row to form a receiving hole for receiving a wire for transmitting a driving force,
Of the two adjacent cylindrical bodies,
One of the cylindrical bodies has an insertion portion having a reduced diameter at an end portion adjacent to the other cylindrical body,
The other cylindrical body has an inner hole that is expanded in diameter at an end adjacent to the one cylindrical body so that the inner hole is aligned with the insertion portion, and an insertion receiving portion is provided to receive the insertion portion so that the axis of the other cylindrical body can be tilted relative to the axis of the one cylindrical body,
when the insertion portion is inserted into the insertion portion and the axis of one of the cylindrical bodies is tilted by a predetermined angle with respect to the axis of the other cylindrical body, inner circumferential surfaces of the two cylindrical bodies on the tilting direction side continuously form one circular arc in a cross section including the two axes,
The inserting portion and the inserted portion are provided with a restricting mechanism that restricts the axis of one of the cylindrical bodies from tilting by a predetermined angle or more relative to the axis of the other cylindrical body,
the restriction mechanism includes an annular shoulder surface having an annular shape centered on the axis and provided at a base end of the insertion portion, and an annular protruding end surface having an annular shape centered on the axis and provided at a protruding end of the inserted portion,
When the insertion portion is inserted into the insertion portion and the axis of one of the cylindrical bodies is tilted by the angle with respect to the axis of the other cylindrical body, the annular shoulder surface abuts against the annular protruding end surface,
The annular shoulder surface has an outer peripheral surface shape of a right circular truncated cone,
The annular end surface has an inner peripheral surface shape of an inverted truncated cone,
the sum of an angle between the annular shoulder surface and the axis and an angle between the annular end surface and the axis is greater than 180 degrees;
A casing in which, when one of the cylindrical bodies is tilted at the specified angle relative to the other cylindrical body, the annular shoulder surface and the annular end surface are in line contact within a plane including the two axes . The insertion portion is provided with a convex sliding surface having a convex spherical shape on an outer periphery thereof,
The insert portion has an inner periphery provided with a concave sliding surface having a concave spherical shape,
2. The casing according to claim 1 , wherein the convex sliding surface and the concave sliding surface have complementary shapes such that they can slide against each other. a first cylindrical body having the insertion portion at both ends and a second cylindrical body having the inserted portion at both ends,
The casing according to claim 1 or 2 , wherein the first cylindrical bodies and the second cylindrical bodies are arranged alternately. The casing according to claim 3 , wherein a wall surface defining the inner hole of the second cylindrical body is raised toward the axis between the inserted portions. 5. The casing according to claim 1, wherein the cylindrical body has the insertion portion at one end and the inserted portion at the other end.

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