Wave Spring Flat Joint Structure for Accurate Laser Welding

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Solution Overview

Problem

The existing wave spring design faces challenges in accurately joining end surfaces of an annular body due to inclined surfaces, making it difficult to stabilize the shape and perform precise welding, especially with general-purpose welding machines.

Innovation Solution

A wave spring design featuring an annular body with crests and valleys alternately formed in the circumferential direction, where at least a portion is a flat surface orthogonal to the center axis for precise joining, allowing for easier stabilization and accurate welding using general-purpose machines, such as laser welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the end surfaces of the annular body are inclined with respect to the center axis, then the wave spring can be formed by joining C-shaped spring material, but the relative position of end surfaces becomes unstable and welding accuracy deteriorates

Engineering Contradiction:
Improveease of joining spring materialVSAvoidwelding accuracy
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The end surfaces of the annular body are designed with different orientations: the heat input surfaces are made parallel to the plane orthogonal to the center axis for accurate welding, while the outer peripheral surfaces maintain the inclined configuration for proper spring function. This local differentiation allows both welding accuracy and spring performance to be achieved simultaneously.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The spring material is pre-formed into a corrugated shape with predetermined crests and valleys before joining. This preliminary forming ensures that when the end surfaces are joined in a parallel configuration, the resulting annular body automatically achieves the desired inclined outer peripheral surfaces for spring functionality without compromising welding accuracy.

Inventive Principle:
Principle #10Preliminary action

2Shape

If the heat input surface is inclined with respect to the plane orthogonal to the center axis, then the wave spring structure is achieved, but the heat input direction cannot be orthogonal to the heat input surface with general-purpose welding machines

Engineering Contradiction:
Improvewave spring structureVSAvoidheat input accuracy
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The wave spring structure is achieved through local inclination of the outer peripheral surfaces while maintaining parallel orientation of the heat input surfaces. This allows the bulk structure to have the required inclined geometry for spring function, while the specific welding surfaces remain orthogonal to accommodate general-purpose welding machines.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The annular body is conceptually segmented into different functional zones: the heat input surfaces are separated and oriented parallel to the orthogonal plane for welding, while the outer peripheral surfaces are allowed to be inclined for spring functionality. This segmentation resolves the conflict between structural requirements and welding requirements.

Inventive Principle:
Principle #1Segmentation

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

This design enables more accurate and stable joining of wave spring end surfaces, reducing stress concentration and failure risk, while allowing for balanced biasing forces and improved strength through strategic placement of the flat portion between crests and valleys.

Implementation Method 1

the joined portion of the annular body is a flat portion extending in a plane orthogonal to a center axis of the annular body

Methodology Applied
Scientific EffectGeometric constraint: Geometry

Implementation Method 2

when the laser light is radiated in a direction perpendicular to the upper surface of the welding worktable, the laser light is radiated naturally perpendicular to an irradiated surface (a surface of the flat portion)

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 3

in a case where the annular body is elastically deformed, a large stress is suppressed from locally acting on both ends of the flat portion

Methodology Applied
Scientific EffectStress distribution: Elasticity

Data Source

PatentEP3736463B1Wave spring
Publication Date: 2023.09.06 NHK SPRING CO LTD
  • EP3736463B1 patent drawingFigure 1
  • EP3736463B1 patent drawingFigure 2
  • EP3736463B1 patent drawingFigure 3

AI summary

A wave spring (1A) includes an annular body (10) in which crests (11) and valleys (12) are alternately and continuously formed in a circumferential direction. At least a portion of the annular body (10) in the circumferential direction is a joined portion. The joined portion of the annular body (10) is a flat portion (13) extending in a plane orthogonal to a center axis (O) of the annular body (10).