Wave Washer Flexible Member for Compact Robot Joint Bending
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Solution Overview
Problem
There is a limit in securing load resistance and flexibility while achieving a reduction in size for flexible members used in joint functioning parts of robots and similar devices.
Innovation Solution
A flexible member is designed with a main body part composed of stacked wave washers having closed ring shapes, joined by linearly separated welded parts that allow for elastic deformation and bending, which helps in achieving excellent load resistance and flexibility while reducing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a coil spring is used to provide high degree of freedom for bending operation, then flexibility is improved, but size reduction is limited due to the need to secure load resistance
Solution Approach 1:
The flexible member is segmented into multiple wave washers stacked in the axial direction, with each wave washer being a thin-walled cylindrical structure. This segmentation allows the flexible member to achieve flexibility through the collective deformation of multiple small units rather than requiring a single large coil spring, thus enabling size reduction while maintaining bending freedom
Solution Approach 2:
The invention transitions from a traditional coil spring structure to a stacked wave washer structure, changing the dimensional arrangement from a single helical element to multiple planar elements stacked axially. This dimensional change allows the flexible member to achieve comparable flexibility with a more compact overall volume
2Strength
If wave washers are stacked and joined to reduce size, then flexibility and load resistance are improved, but stress deviation occurs during bending
Solution Approach 1:
The joint parts are designed with an asymmetric configuration where the welded portions are positioned at specific locations on the wave washers. This asymmetric positioning of welds creates a stress distribution pattern that compensates for the natural stress concentration that would occur in symmetric configurations, thereby reducing overall stress deviation during bending operations
Solution Approach 2:
The joint parts are pre-designed with specific welded portion arrangements before the flexible member is assembled. This preliminary design of the joint geometry ensures that when the wave washers are stacked and subjected to load, the stress is distributed more uniformly across the structure, preventing excessive stress concentration at any single point
3Reliability
If the flexible member is designed for excellent load resistance and flexibility, then durability is improved, but the structure becomes more complex
Solution Approach 1:
The flexible member uses multiple identical wave washers with uniform geometry and material properties stacked in sequence. This homogeneous design allows for simplified manufacturing and assembly while achieving improved durability through the cumulative effect of multiple identical units, each contributing to the overall load resistance and flexibility without requiring complex varying structures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The flexible member exhibits improved durability and load resistance with enhanced flexibility, allowing for efficient bending operations and reduced stress deviation, thereby improving the overall performance and longevity of the joint functioning parts.
Implementation Method 1
the main body part is able to be bent with respect to the axial direction due to elastic deformation of the wave washers
Implementation Method 2
a pair of welded parts in linear shape, being gradually separated from each other in a circumferential direction
Data Source
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AI summary
A flexible member is provided which can have excellent load resistance and flexibility while being more compact. This flexible member has a main body 19 which comprises multiple annular wave washers 23 laminated in the axial direction and bonded together by multiple bonding units 21, and which is bendable in the axial direction through elastic deformation of the wave washers 23. The bonding units 21 comprise a pair of linear welded parts 25a, 25b which, from the inner surface 23e towards the outer surface 23f of the wave washers 23, gradually become further apart from each other in the circumferential direction.