Bent structure and manufacturing method thereof

Abstract

To provide a bending structure of a multijoint function formed by connecting multiple bending parts in each of which multiple wave washers are laminated and welded to each other.SOLUTION: A bending structure includes: a first bending part 7 and a second bending part 9 which may bend and extend; and a connection part 11 which is welded between the first bending part 7 and the second bending part 9 in an axial direction and has rigidity higher than those of the first bending part 7 and the second bending part 9. The first bending part 7 and the second bending part 9 include multiple wave washers 13 which are laminated in the axial direction and welded to each other. The connection part 11 has a circle shape in which an inner periphery and an outer periphery are continuous in a circumferential direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a bending structure to be used in a joint function part of a robot or the like, and a manufacturing method thereof. [Background technology]

[0002] A conventional bent structure is known that has a bent portion in which a plurality of wave washers are stacked and welded together, as in Patent Document 1. A bent structure using this bent portion can be made small in diameter while having excellent load resistance and flexibility.

[0003] On the other hand, in a bent structure, multiple bends may be connected to provide a multi-joint function. Such a bent structure having a multi-joint function is expected to be able to be made smaller in diameter by applying a bent portion in which multiple wave washers are stacked and welded.

[0004] However, in such a bending structure having a multi-joint function, it is difficult to shorten the distance between the bending portions and connect them integrally while enabling the diameter to be reduced. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-172001 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problem to be solved was that in a multi-joint bending structure in which multiple wave washers are stacked and welded together to connect multiple bending sections, it was difficult to reduce the diameter of the bending structure while shortening the distance between the bending sections and connecting them as a single unit. [Means for solving the problem]

[0007] The present invention provides a bent structure comprising: a first bent portion and a second bent portion capable of bending and extending; and a connection portion welded in the axial direction between the first bent portion and the second bent portion and having higher rigidity than the first bent portion and the second bent portion, wherein the first bent portion and the second bent portion each comprise a plurality of wave washers stacked in the axial direction and welded to each other, and the connection portion has a circular shape whose inner and outer circumferences are each continuous in the circumferential direction.

[0008] The present invention also provides a method for manufacturing a bent structure, comprising stacking and welding the multiple wave washers of the first bent portion sequentially from one side of the axial direction of the connection portion, and welding the multiple wave washers of the second bent portion sequentially from the other side of the axial direction of the connection portion. Effect of the Invention

[0009] According to the present invention, in a bending structure with a multi-joint function in which multiple bending sections are connected by stacking multiple wave washers and welding them together, the distance between the bending sections can be shortened and connected together while reducing the overall diameter. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a bent structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of the bending structure of FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view of the bent structure of FIG. [Figure 4] FIG. 4 is a plan view of a wave washer used in the bent structure of FIG. [Diagram 5] FIG. 5 is a plan view of a flat washer used in the bent structure of FIG. [Figure 6] FIG. 6 is a plan view showing a connection portion used in the bent structure of FIG. [Figure 7] FIG. 7 is a side view showing a manufacturing method of the bent structure according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a side view showing a manufacturing method of the bent structure according to the first embodiment of the present invention. [Figure 9] FIG. 9 is a side view showing a method for manufacturing a bent structure according to the first embodiment of the present invention. [Figure 10] FIG. 10 is a side view showing a method for manufacturing a bent structure according to the first embodiment of the present invention. [Figure 11] FIG. 11 is a side view showing a method for manufacturing a bent structure according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In a multi-joint bending structure in which multiple wave washers are stacked and welded together to form multiple bending sections, the objective of reducing the diameter of the bending structure while shortening the distance between the bending sections and connecting them as a single unit has been achieved from both a structural and manufacturing standpoint.

[0012] The bent structure (1) includes a first bent portion (7), a second bent portion (9), and a connecting portion (11). The first bent portion (7) and the second bent portion (9) are bendable and extendable, and each includes a plurality of wave washers (13) that are stacked in the axial direction and welded to each other. The connecting portion (11) is welded in the axial direction between the first bent portion (7) and the second bent portion (9), has higher rigidity than the first bent portion (7) and the second bent portion (9), and has a circular shape in which the inner circumference and the outer circumference are continuous in the circumferential direction.

[0013] The connection portion (11) may have a constant width between the inner and outer circumferences.

[0014] Welding between multiple wave washers (13) may be performed in the intermediate portion between the inner and outer circumferences of each wave washer (13), and the connection portion (11) may be configured to overlap the welded portions (W) of the multiple wave washers (13) in the axial direction.

[0015] One or both of the first bent portion (7) and the second bent portion (9) may be provided with a flat washer (15) constituting the axial end, the flat washer (15) being welded in contact with the connection portion (11) around its entire circumference, and the multiple wave washers (13) may be welded to the connection portion (11) via the flat washer (15).

[0016] A manufacturing method for such a bent structure (1) includes stacking and welding a plurality of wave washers (13) of the first bent portion (7) sequentially from one axial side of the connection portion (11), and welding a plurality of wave washers (13) of the second bent portion (9) sequentially from the other axial side of the connection portion (11).

[0017] When the multiple wave washers (13) and the connection portion (11) have insertion holes (7a, 9a, 11b) for inserting the cord-like members (17a, 17b), a guide member (G) may be inserted into the insertion hole (11b) of the connection portion (11), and when stacking the multiple wave washers (13) of the first bent portion (7) and the second bent portion (9), the guide member (G) may be inserted into the insertion holes (7a, 9a) of the multiple wave washers (13) to position them on the connection portion (11).

[0018] A flat washer (15) may be stacked and welded to one or both of the axial sides of the connection portion (11), and multiple wave washers (13) may be stacked and welded to the flat washer (15) in the axial direction. EXAMPLES

[0019] [Configuration of the bent structure] Fig. 1 is a perspective view showing a bent structure according to Example 1 of the present invention, Fig. 2 is a side view of the bent structure, and Fig. 3 is a schematic cross-sectional view of the bent structure. Note that Figs. 1 to 3 show the same structure, although the shapes of the various parts are slightly different.

[0020] The bending structure 1 is applied to a joint function part of various devices for medical and industrial use, such as a manipulator, a robot, and an actuator. The joint function part is an apparatus, mechanism, device, etc. that has a function as a bending / extending joint.

[0021] The bent structure 1 of this embodiment includes a base portion 3, a movable portion 5, a first bent portion 7, a second bent portion 9, and a connecting portion 11.

[0022] The base 3 is a columnar body, such as a cylindrical body, made of metal, resin, or the like, and is attached to the end of a shaft of a manipulator, etc. The base 3 is not limited to a columnar body, and may have an appropriate shape depending on the device to which the bending structure 1 is applied.

[0023] The base 3 is provided with a radial recess 3a. The recess 3a is provided along the axial direction of the base 3. Due to this recess 3a, the base 3 has a discontinuous outer periphery in the circumferential direction. The recess 3a enables welding to the second bent portion 9 on the base 3 side, as described below.

[0024] The radial direction means a direction along the diameter of the bent structure 1 and includes a direction slightly inclined relative to the diameter. The axial direction means a direction along the axis of the bent structure 1 and includes a direction slightly inclined relative to the axis. The circumferential direction means a direction along the outer periphery of the bent structure 1.

[0025] The movable part 5 is supported by the base part 3 so as to be displaceable in the axial direction by a first bent part 7 and a second bent part 9. An end effector or the like is attached to the movable part 5 according to the device to which the bending structure 1 is applied.

[0026] The movable part 5 is formed as a columnar body as a whole from metal, resin, etc. Like the base part 3, the movable part 5 is formed in an appropriate shape depending on the device to which the bending structure 1 is applied, and is not limited to a columnar body made of metal, resin, etc.

[0027] The movable part 5 has radial recesses 5a formed along the axial direction, similar to the base part 3. Therefore, the movable part 5 has a discontinuous outer periphery in the circumferential direction due to the recesses 5a. The recesses 5a enable welding of the movable part 5 side to the first bent part 7, as described later.

[0028] The first bent portion 7 and the second bent portion 9 are capable of bending and extending, and each includes a plurality of wave washers 13 and a plurality of flat washers 15.

[0029] The first bent portion 7 and the second bent portion 9 basically have the same configuration, but have different axial lengths. In this embodiment, the first bent portion 7 is longer in the axial direction than the second bent portion 9. However, the first bent portion 7 may be shorter in the axial direction than the second bent portion 9. The first bent portion 7 and the second bent portion 9 may also have the same length. Furthermore, the first bent portion 7 and the second bent portion 9 do not have to have the same configuration, such as a configuration in which one has a smaller diameter than the other, or a configuration in which the planar shapes of the wave washers 13 are different from each other.

[0030] The bent structure 1 may have three or more bent portions, and in that case, the tip side relative to the connecting portion 11 is the first bent portion 7, and the base side is the second bent portion 9. The tip and base ends are the tip and base ends of the bent structure 1 in the axial direction.

[0031] FIG. 4 is a plan view showing the wave washer 13. As shown in FIG.

[0032] 1 to 4, a plurality of wave washers 13 are stacked in the axial direction and welded together to maintain the stacked state. Due to elastic deformation of these wave washers 13, the first bent portion 7 and the second bent portion 9 are elastically bendable.

[0033] Each wave washer 13 is a plate material formed into an annular shape from a metal, etc. The wave washer 13 in this embodiment is a circular plate material made of stainless steel, and the radial width between the inner and outer periphery and the plate thickness are constant.

[0034] The wave washer 13 is welded to the adjacent wave washer 13 at the abutting portion. This welding is performed at the intermediate portion between the inner periphery and the outer periphery of each wave washer 13.

[0035] The intermediate portion between the inner circumference and the outer circumference of each wave washer 13 means the region between the inner circumference and the outer circumference excluding the inner circumference and the outer circumference, and does not mean the central position of the width between the inner circumference and the outer circumference. Therefore, welding of the intermediate portion between the inner circumference and the outer circumference can be performed not only at the central position of the width between the inner circumference and the outer circumference, but also at a position offset from the central position toward the inner circumference or the outer circumference. This welding can also be performed at multiple points aligned in the radial direction of the intermediate portion between the inner circumference and the outer circumference. The welding may be performed on the inner circumference and the outer circumference of each wave washer 13.

[0036] Specifically, the wave washer 13 has a plurality of peaks 13a in the circumferential direction, and has valleys 13b between adjacent peaks 13a. Between adjacent wave washers 13 in the axial direction, the peaks 13a of one wave washer 13 abut against the valleys 13b of the other wave washer. At these abutting peaks 13a and valleys 13b, intermediate portions between the inner circumference and the outer circumference are joined by a weld W by laser welding or the like.

[0037] The peaks 13a and the valleys 13b do not have to be in contact with each other, and may be in contact with the inclined portions 13c, for example, while being shifted from each other in the circumferential direction. The shape, material, etc. of the wave washer 13 can be appropriately changed according to the required characteristics, etc.

[0038] FIG. 5 is a plan view showing the flat washer 15. As shown in FIG.

[0039] 1 to 3 and 5, the plurality of flat washers 15 constitute both axial ends of the first bent portion 7 and the second bent portion 9, and are welded to each other, to adjacent wave washers 15, and to the connecting portion 11, the base portion 3 or the movable portion 5. In other words, the plurality of wave washers 13 are welded to the connecting portion 11 via the plurality of flat washers 15.

[0040] The flat washer 15 may be provided only on both ends of one of the first bent portion 7 and the second bent portion 9. The flat washer 15 may be provided only on one end of one or both of the first bent portion 7 and the second bent portion 9. Furthermore, the flat washer 15 may be omitted.

[0041] In addition, in this embodiment, the number of flat washers 15 is three, but this can be arbitrarily changed to one, two, four or more.

[0042] The welded portion W between the flat washer 15 and the wave washer 13 is formed in the middle of the inner periphery and the outer periphery at the contact portion between the flat washer 15 and the wave washer 13.

[0043] The welds W between the flat washers 15, the welds W between the flat washers 15 and the base 3 and the movable part 5, and the welds W between the flat washers 15 and the connecting part 11 are formed in the middle of the inner and outer circumferences at positions that are sequentially displaced circumferentially, following the connection between the wave washers 13.

[0044] Each flat washer 15 is a plate material formed into an annular shape from metal or the like, is made of the same material as the wave washer 13, has the same inner and outer diameters and plate thickness, and is formed flat.

[0045] When the first bent portion 7 and the second bent portion 9 are bent, the flat washer 15 deforms together with the wave washer 13 so as to open up the space between them, but the amount of deformation is smaller than that of the wave washer 13. The flat washer 15 may be formed using a material different from that of the wave washer 13.

[0046] FIG. 6 is a plan view showing the connection portion 11. As shown in FIG.

[0047] 1 to 3 and 6, the connecting portion 11 is welded between the first bent portion 7 and the second bent portion 9 in the axial direction, and is a member having higher rigidity than the first bent portion 7 and the second bent portion 9. The rigidity refers to bending rigidity in the axial direction. The connecting portion 11 constitutes a multiple joint by connecting the first bent portion 7 and the second bent portion 9.

[0048] The connecting portion 11 has a circular shape in which the inner circumference and the outer circumference are continuous in the circumferential direction. Here, "continuous" means that the inner circumference or the outer circumference is not discontinuous due to recesses or notches along the axial direction for welding to the ends of the first bent portion 7 and the second bent portion 9, and also includes cases where the inner circumference or the outer circumference is discontinuous due to slight recesses or the like.

[0049] The connecting portion 11 in this embodiment is cylindrical, and the width between the inner circumference and the outer circumference is constant. In order to make the width between the inner circumference and the outer circumference constant, it is sufficient that the connecting portion 11 has a planar shape without corners. Therefore, the connecting portion 11 may be shaped like an elliptical cylinder, etc. Also, the connecting portion 11 may be shaped like a rectangular cylinder, in which the width between the inner circumference and the outer circumference is not constant. Furthermore, the connecting portion 11 may have a diameter of one or both of the inner circumference and the outer circumference that changes in the axial direction. In this case, it is possible to connect bent portions with different diameters.

[0050] The connection portion 11 of this embodiment overlaps in the axial direction with a welded portion W which is a welded portion of the wave washers 13 and the flat washers 15. This allows the connection portion 11 to reliably receive the first bent portion 7 and the second bent portion 9, and stabilize the operation.

[0051] A flat circular joint surface 11a with a constant width is formed on both axial sides of the connection portion 11. The flat washer 15 coupled to the connection portion 11 is evenly abutted against the connection portion 11 over the entire circumference due to the joint surface 11a. In this state, the flat washer 15 is welded to the connection portion 11. Therefore, the connection portion 11 can receive the first bent portion 7 and the second bent portion 9 more reliably and stabilize its operation.

[0052] The connection portion 11 is provided with an insertion hole 11b and a holding portion 11c for wires 17a and 17b, which are rope-like members. Note that the rope-like members include those for operating the bending structure 1 like the wires 17a and 17b, as well as for carrying electricity and for guiding. The guide members guide the rope-like members for operation and for carrying electricity.

[0053] As the cord-like member, in addition to the wires 17a and 17b, it is possible to adopt appropriate ones such as a single wire, a twisted wire, a piano wire, a multi-joint rod, a chain, a string, a thread, a rope, etc. As the material of the cord-like member, it is possible to adopt appropriate ones such as metals such as stainless steel, NiTi (nickel titanium), carbon steel, etc.

[0054] A plurality of insertion holes 11b are provided in the circumferential direction of the connection portion 11. The insertion holes 11b penetrate the connection portion 11 in the axial direction. The insertion holes 11b communicate with the insertion holes 7a, 9a of the first bent portion 7 and the second bent portion 9 in the axial direction.

[0055] The insertion holes 7a, 9a are provided penetrating the wave washer 13 and the flat washer 15. In this embodiment, the insertion holes 7a, 9a communicate with each other in the axial direction, but they may be formed at positions displaced in the circumferential direction on the adjacent wave washer 13 and flat washer 15.

[0056] In the bending structure 1, the wire 17a for operating the first bending portion 7 is guided by being inserted in the axial direction from the second bending portion 9 side through the connection portion 11 to the first bending portion 7 through the insertion holes 7a, 9a, and 11b.

[0057] The wire 17a inserted through the first bent portion 7 has its tip held by the movable portion 5, and the first bent portion 7 is bent by pulling on the base end side, making it possible to displace the movable portion 5.

[0058] The holding portion 11c of the connection portion 11 holds the tip of the wire 17b for manipulating the second bent portion 9. This holding portion 11c is formed in the middle of the connection portion 11 in the axial direction and is formed of a space portion that is open on the outer periphery.

[0059] Therefore, although the connection portion 11 loses its outer circumferential continuity due to the holding portion 11c, the continuity is maintained on both sides in the axial direction.

[0060] The holding portion 11c communicates with the insertion hole 11b of the connection portion 11. The insertion hole 11b communicates with the insertion hole 9a of the second bent portion 9 in the axial direction. This allows the wire 17b for operating the second bent portion 9 to be inserted and guided in the axial direction through the second bent portion 9 to the connection portion 11.

[0061] The tip of the wire 17b is held by the holding portion 11c of the connection portion 11, and the second bent portion 9 is bent by pulling on the base end side, making the connection portion 11 displaceable.

[0062] In this embodiment, the tip of the wire 17b is held by an end processing member 18, such as a sleeve, attached to the tip of the wire 17b engaging with the holding portion 11c.

[0063] The holding of the tip of the wire 17b is not limited to the engagement of the end processing member 18 with the holding portion 11c, but can be performed by any appropriate method, and the holding portion 11c may be omitted.

[0064] [Manufacturing method of bent structure] 7 to 11 are side views showing a manufacturing method of the bent structure 1. FIG.

[0065] In the manufacturing method of the bent structure 1 of this embodiment, the first bent portion 7 and the second bent portion 9 are attached to the connecting portion 11 as shown in FIGS.

[0066] First, one axial side of the connection portion 11 is placed facing upward as shown in Fig. 7. This placement may be performed using an appropriate holder.

[0067] In this state, the guide member G is inserted into the insertion hole 11b of the connection portion 11. A rod-shaped or cord-shaped member is used as the guide member G. The guide member G preferably has a rigidity sufficient to be able to stand on its own.

[0068] 8 and 9, the first bent portion 7 is attached to the connecting portion 11. Specifically, a plurality of flat washers 15 of the first bent portion 7 are stacked on one axial side of the connecting portion 11 and welded. The welding may be performed using an appropriate method such as a carbon dioxide laser, a YAG (Yttrium Aluminum Garnet) laser, or a fiber laser.

[0069] A plurality of wave washers 13 are sequentially stacked and welded to the stacked flat washers 15. In this way, the plurality of wave washers 13 are sequentially stacked and welded from one side of the connection portion 11 in the axial direction.

[0070] When stacking the flat washers 15 and the wave washers 13, the flat washers 15 and the wave washers 13 can be positioned relative to the connection portion 11 by inserting the guide member G into the insertion hole 7a provided in the flat washer 15 and the wave washer 13 of the first bend portion 7. The guide member is not limited to being inserted into the insertion hole 7a. For example, the guide member may be one positioned outside the flat washer 15 and the wave washer 13, such as one that guides the outer periphery of the flat washer 15 and the wave washer 13, or one positioned inside the flat washer 15 and the wave washer 13, such as one that guides the inner periphery of the flat washer 15 and the wave washer 13.

[0071] After the flat washers 15 and the wave washers 13 of the first bending portion 7 are laminated, the movable portion 5 is laminated.

[0072] At this time, the flat washer 15 of the first bent portion 7 is attached by welding to the joining surface 5b of the movable portion 5 to the first bent portion 7. On the other hand, two flat washers 15, one less, are stacked on the end of the first bent portion 7 to which the movable portion 5 is attached.

[0073] The flat washer 15 connected to the movable part 5 is then laminated on this flat washer 15 and welded to the movable part 5 via the recess 5a.

[0074] After the first bent portion 7 is connected to the connecting portion 11 in this manner, the other axial side of the connecting portion 11 is placed facing upward, as shown in FIG.

[0075] In this state, the second bent portion 9 is attached to the connecting portion 11 as shown in Fig. 11. Specifically, the flat washers 15 and the wave washers 13 of the second bent portion 9 are welded while being stacked in order from the other axial side of the connecting portion 11.

[0076] When stacking multiple flat washers 15 and multiple wave washers 13, as in the first bend portion 7, they can be positioned relative to the connection portion 11 by inserting a guide member G into the insertion holes 9a provided in the flat washers 15 and wave washers 13 of the second bend portion 9.

[0077] After the flat washers 15 and the wave washers 13 of the second bent portion 9 are laminated, the base portion 3 is laminated.

[0078] The lamination of the base 3 can be performed in the same manner as the lamination of the movable part 5 to the first bent part 7. That is, the base 3 with the flat washer 15 of the second bent part 9 attached to the joining surface 3a by welding is laminated on the end part of the second bent part 9 on which two flat washers 15 (one less) have been laminated.

[0079] Then, the flat washer 15 on the second bent portion 9 side and the flat washer 15 on the base portion 3 side are welded together via the recess 3a of the base portion 3 in a stacked state.

[0080] In this way, the movable part 5 and the base part 3 are attached to the connection part 11 via the first bent part 7 and the second bent part 9. Thereafter, when the guide member G is pulled out from the base part 3 side, the bent structure 1 is completed.

[0081] In this embodiment, the first bent portion 7 and the second bent portion 9 are attached to the connecting portion 11 in this order, but the first bent portion 7 and the second bent portion 9 may be attached in any order. For example, the second bent portion 9 may be attached to the connecting portion 11 before the first bent portion 7. Also, the wave washers 13 of the first bent portion 7 and the second bent portion 9 may be alternately stacked while the connecting portion 11 is reversed in the axial direction.

[0082] By this manufacturing method, the bent structure 1 of this embodiment does not need to have a recess for welding in the connection portion 11, and the inner and outer peripheries of the connection portion 11 can be formed into a continuous circular shape in the circumferential direction.

[0083] In this bent structure 1, the diameter of the connection portion 11 can be reduced, and it is possible to shorten the distance between the bent portions 7 and 9 while reducing the diameter of the bent structure 1, and to connect them integrally.

[0084] That is, when providing the connection part 11 with a recess for welding like the base part 3 and the movable part 5, reducing the diameter of the connection part 11 increases the proportion of the recess in the connection part 11. With this structure, the load of the wire 17b cannot be supported, and there is a limit to reducing the diameter and shortening the axial length.

[0085] In contrast, in the bent structure 1 of this embodiment, even if the connecting portion 11 is reduced in diameter or shortened in the axial direction, the load of the wire 17b can be received by the continuous winding shape of the inner and outer circumferences in the circumferential direction. As a result, the bent structure 1 can accommodate a reduction in the overall diameter. [Explanation of symbols]

[0086] 1 Bent structure 7 1st bending part 7a, 9a Insertion holes 9 Second bending part 11 Connection 13 Wave Washer 15 Flat washer 17a, 17b Wire (cord-like member) G Guide material

Claims

1. A first bending portion and a second bending portion capable of bending and extending; a connection portion welded between the first bent portion and the second bent portion in the axial direction and having a higher rigidity than the first bent portion and the second bent portion, The first bent portion and the second bent portion each include a plurality of wave washers stacked in the axial direction and welded to each other, The connection portion has an inner periphery and an outer periphery each having a circular shape that is continuous in the circumferential direction. bending structure.

2. 2. The bent structure according to claim 1, The connection portion has a constant width between the inner circumference and the outer circumference. bending structure.

3. The bent structure according to claim 1 or 2, The welding between the plurality of wave washers is performed at an intermediate portion between the inner circumference and the outer circumference of each wave washer, The connection portion overlaps the welded portions of the plurality of wave washers in the axial direction. bending structure.

4. The bent structure according to any one of claims 1 to 3, one or both of the first bent portion and the second bent portion include a flat washer forming an axial end portion; The flat washer is welded in contact with the connection portion over its entire periphery, The plurality of wave washers are welded to the connection portion via the flat washer. bending structure.

5. A method for manufacturing a bent structure according to any one of claims 1 to 3, comprising the steps of: The plurality of wave washers of the first bent portion are sequentially stacked and welded from one side of the connection portion in the axial direction, The plurality of wave washers of the second bent portion are sequentially stacked and welded from the other side of the connection portion in the axial direction. A method for manufacturing a bent structure.

6. A method for manufacturing a bent structure according to claim 5, The plurality of wave washers and the connection portion each have an insertion hole for inserting a cord-like member therethrough, A guide member is inserted into the insertion hole of the connection portion, When stacking the plurality of wave washers of the first bent portion and the second bent portion, the guide member is inserted through insertion holes of the plurality of wave washers to position them on the connection portion. A method for manufacturing a bent structure.

7. A method for manufacturing a bent structure according to claim 5 or 6, comprising the steps of: A flat washer is stacked and welded to one or both of the axial sides of the connection portion, and the plurality of wave washers are sequentially stacked and welded to the flat washer in the axial direction. A method for manufacturing a bent structure.

8. A bent structure according to claim 1, The welding between the first bent portion and the connection portion and the welding between the second bent portion and the connection portion are performed at welded portions located between the plurality of wave washers and the connection portion in the axial direction, and the welded portions are located in intermediate portions between the inner circumference and the outer circumference of the plurality of wave washers in the radial direction. bending structure.

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