Spring-Biased Friction Stir Welding Tool for Load Control

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Solution Overview

Problem

Existing joining devices for friction stir welding, particularly those using load control, have a complex structure and are expensive, necessitating a rotating tool capable of performing load control that can be fitted to a relatively-low cost machining center.

Innovation Solution

A rotating tool with a stir pin and shoulder assembly biased by elastic members, restricted by restriction members, allowing for load control and integration with a machining center, enabling precise insertion and pressure application during friction stir welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If load control is implemented using a robot arm joining device, then joining quality is improved, but device complexity and cost increase

Engineering Contradiction:

Improvejoining qualityVSAvoiddevice structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the complex robot arm load control system with a simpler elastic member-based load control mechanism. The elastic member (spring) automatically controls the pressing force during friction stir welding, eliminating the need for complex sensors, controllers, and actuators required in robot arm systems. This mechanical substitution maintains joining quality while significantly reducing device complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The elastic member performs load control autonomously without requiring external control systems. The spring automatically adjusts the pressing force based on the reaction force from the workpiece, creating a self-regulating load control system that simplifies the overall device architecture while maintaining consistent joining quality.

Inventive Principle:

Principle #25Self-service

2Manufacturing precision

If load control is implemented using a robot arm joining device, then joining quality is improved, but device cost increases

Engineering Contradiction:

Improvejoining qualityVSAvoiddevice cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive robot arm load control systems with inexpensive elastic members. The spring-based mechanism uses simple mechanical components that are much cheaper than robot arms equipped with load sensors and control systems, while still achieving consistent joining quality through automatic load control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The elastic member is a simple, inexpensive component that can be easily replaced if needed. This approach uses low-cost mechanical elements rather than expensive robotic systems, making the joining device more affordable while maintaining effective load control for consistent joining quality.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If position control is used in a machining center, then device cost is reduced, but load control capability is lost

Engineering Contradiction:

Improvedevice costVSAvoidload control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent introduces an elastic member into the machining center's tool holder to provide load control capability. The spring automatically compensates for position variations and maintains consistent pressing force during friction stir welding, enabling load control in a machining center without requiring expensive robot arm systems or complex control modifications.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables stable and efficient insertion of the stir pin into various materials while controlling load, reducing weld flash and maintaining consistent joining quality despite variations in material height, and preventing elastic member breakage.

Implementation Method 1

a first elastic member configured to bias the assembly toward a distal end side of the stir pin in the axial direction of the rotating shaft

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

the stir pin configured to perform friction stirring on the to-be-joined members by being inserted into the to-be-joined members

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

a joining device configured to perform friction stir welding of to-be-joined members

Methodology Applied

Scientific EffectFriction stir welding: Friction Welding

Data Source

PatentUS12558738B2Rotating tool, joining device, and joining method

Publication Date: 2026.02.24 NIPPON LIGHT METAL CO LTD

AI summary

Provided is a rotating tool used in a joining device configured to perform friction stir welding of to-be-joined members, the rotating tool including: a main body; a stir pin configured to perform friction stirring on the to-be-joined members; a shoulder configured to press the to-be-joined members, the stir pin and the shoulder forming an assembly; a first elastic member configured to bias the assembly toward a distal end side of the stir pin; and a first restriction member configured to restrict movement of the assembly toward a base end side in the axial direction of the rotating shaft, and the first restriction member restricts the movement of the assembly such that an amount of deformation occurring in the first elastic member with the movement of the assembly does not exceed a maximum allowable amount of the first elastic member.