US-20260124772-A1 - BENDING STRUCTURE AND SEMI-FINISHED PRODUCT THEREOF

US20260124772A1US 20260124772 A1US20260124772 A1US 20260124772A1US-20260124772-A1

Abstract

A bending structure includes: a core material resisting a compressive force in an axial direction and having flexibility allowing bending; an elastic member located parallel with the core material and compressible in the axial direction; a base part receiving one axial side of the core material and the elastic member; and a movable part receiving the other axial side of the core material and the elastic member. In a state in which the elastic member is received by the base part and the movable part and is non-compressed, the core material has an axial length shorter than an axial length between the receiving parts of the base part and the movable part. The elastic member receives and is compressed by a load in the axial direction corresponding to a spacing between the base part and the movable part and imparts an urging force.

Inventors

Yuki HOTODA
Masahiro Inaba

Assignees

NHK SPRING CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20231002
Priority Date: 20221003

Claims (7)

1 . A bending structure capable of bending from an extended state to a bent state, the bending structure comprising: a core material resisting a compressive force in an axial direction and having flexibility allowing the bending; an elastic member located parallel with the core material and compressible in the axial direction; a one-side receiving member having a receiving part that receives one axial side of the core material and the elastic member; and an other-side receiving member having a receiving part that receives another axial side of the core material and the elastic member, wherein in a state in which the elastic member is received by the one-side receiving member and the other-side receiving member and is non-compressed, the core material has a length in the axial direction that is shorter than a length in the axial direction between the receiving parts, which receive the core material, of the one-side receiving member and the other-side receiving member, and the elastic member receives and is compressed by a load in the axial direction corresponding to a spacing between the one-side receiving member and the other-side receiving member and imparts an urging force.
2 . The bending structure according to claim 1 , wherein the core material is interposed in a non-compressed state between the abutting receiving parts of the one-side receiving member and the other-side receiving member.
3 . The bending structure according to claim 1 , wherein the elastic member is compressed by an amount equal to or greater than a difference between the length of the core material in the axial direction and the length in the axial direction between the receiving parts.
4 . The bending structure according to claim 1 , wherein the core material is a multi-flexible body comprising an outer coil spring and an inner coil spring disposed on an inner side of the outer coil spring, and a wire of the inner coil spring fits between a wire of the outer coil spring.
5 . The bending structure according to claim 1 , comprising: a spacing adjustment part adjusting the spacing between the one-side receiving member and the other-side receiving member.
6 . The bending structure according to claim 5 , wherein the spacing adjustment part comprises a plurality of cord-shaped members having one side fixed to the one-side receiving member and another side routed through the other-side receiving member, to serve to operate the bending from the extended state to the bent state, and the cord-shaped members are used for adjustment of the spacing.
7 . A semi-finished product of a bending structure capable of bending from an extended state to a bent state, the semi-finished product of the bending structure comprising: a core material resisting a compressive force in an axial direction and having flexibility allowing the bending; an elastic member located parallel with the core material and compressible in the axial direction; a one-side receiving member having a receiving part that receives one axial side of the core material and the elastic member; and an other-side receiving member having a receiving part that receives another axial side of the core material and the elastic member, wherein the elastic member is in a non-compressed state received by the one-side receiving member and the other-side receiving member, and the core material has a length in the axial direction that is shorter than a length in the axial direction between the receiving parts, which receive the core material, of the one-side receiving member and the other-side receiving member.

Description

TECHNICAL FIELD The present invention relates to a bending structure and a semi-finished product thereof provided for a robot and the like. RELATED ART A robot, a manipulator, an actuator, etc. may include a joint functional part that enables bending and extending. A bending structure such as the one described in Patent Document 1, for example, is used in such a joint functional part. In the bending structure of Patent Document 1, an inner coil part and an outer coil part, which serve as a core material, and bellows, which serve as an elastic member on a radially outer side thereof, are disposed between a base part and a movable part, which serve as a one-side receiving member and an other-side receiving member. The bending structure is configured to perform a bending action by stretching a drive wire joined to the movable part in an axial direction. In addition, during the bending action, unintended compression in the axial direction is suppressed by the inner and outer coil parts to stabilize the action. In such a bending structure, an urging force is imparted to urge the base part and the movable part to separate from each other in the axial direction, and slack in the drive wire is prevented. This urging force may be set by compressing the inner and outer coil parts and the bellows in the axial direction with a load corresponding to a spacing between the base part and the movable part. However, the load applied when setting the urging force is mainly received by the inner and outer coil parts, which serve as the core material. As a result, flexibility of the inner and outer coil parts may be affected, and an abnormality may occur in the bending action of the bending structure. Similarly, such an issue also occurs in the case of using another core material such as a close-contact spring or a columnar body instead of the inner and outer coil parts. RELATED ART DOCUMENTS Patent Documents Patent Document 1: Japanese Patent Application Laid-Open No. 2020-26021 SUMMARY OF INVENTION Problem to Be Solved by Invention The problem to be solved lies in that, in the case where an urging force is imparted to a bending structure, an abnormality may occur in a bending action of the bending structure. Means for Solving Problem The present invention provides a bending structure capable of bending from an extended state to a bent state. The bending structure includes a core material, an elastic member, a one-side receiving member, and an other-side receiving member. The core material resists a compressive force in an axial direction and has flexibility allowing the bending. The elastic member is located parallel with the core material and is compressible in the axial direction. The one-side receiving member has a receiving part that receives one axial side of the core material and the elastic member. The other-side receiving member has a receiving part that receives another axial side of the core material and the elastic member. In a state in which the elastic member is received by the one-side receiving member and the other-side receiving member and is non-compressed, the core material has a length in the axial direction that is shorter than a length in the axial direction between the receiving parts, which receive the core material, of the one-side receiving member and the other-side receiving member. The elastic member receives and is compressed by a load in the axial direction corresponding to a spacing between the one-side receiving member and the other-side receiving member and imparts an urging force. In addition, the present invention provides a semi-finished product of a bending structure capable of bending from an extended state to a bent state. The semi-finished product of the bending structure includes a core material, an elastic member, a one-side receiving member, and an other-side receiving member. The core material resists a compressive force in an axial direction and has flexibility allowing the bending. The elastic member is located parallel with the core material and is compressible in the axial direction. The one-side receiving member has a receiving part that receives one axial side of the core material and the elastic member. The other-side receiving member has a receiving part that receives another axial side of the core material and the elastic member. The elastic member is in a non-compressed state received by the one-side receiving member and the other-side receiving member. The core material has a length in the axial direction that is shorter than a length in the axial direction between the receiving parts, which receive the core material, of the one-side receiving member and the other-side receiving member. Effects of Invention According to the present invention, in the case where an urging force is generated in the bending structure, the load applied to the core material can be alleviated to suppress an abnormality in the bending action. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspecti