Friction Stir Welding Tool With Planetary Gear Speed Split

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing stirring frame welding tools face challenges in achieving high rotation speeds for the pin while avoiding unfavorable high speeds at the shoulder, which can negatively impact the quality of the welding seam, and are often complex and difficult to manufacture and handle.

Innovation Solution

A stirring frame welding tool utilizing a planetary gear with a hollow wheel, sun wheel, and planetary carrier, where the pin and shoulder are connected to the planetary gear to achieve different rotary speeds in the same rotation direction, allowing for a single drive to control both components and reduce wear on the contact area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the shoulder and pin are rigidly connected and rotate at the same speed, then the structure is simple, but high rotation speed at the pin causes unfavorably high speeds at the shoulder which negatively impact weld quality

Engineering Contradiction:
Improvestructural simplicityVSAvoidweld quality
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The friction stir welding tool is divided into two separate rotating components: the pin and the shoulder. Each component can rotate at different speeds independently, allowing the pin to rotate at high speed for effective mixing while the shoulder rotates at a lower, controlled speed to maintain weld quality. This segmentation resolves the contradiction by enabling differential rotation speeds without requiring a complex multi-drive system.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If separate drives are used for the pin and shoulder to achieve different speeds, then weld quality can be maintained, but the tool becomes complex to manufacture and difficult to handle

Engineering Contradiction:
Improveweld qualityVSAvoidtool complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

A single drive mechanism is used to rotate both the pin and the shoulder simultaneously. The drive is connected to both components through a shared transmission system, allowing differential speeds to be achieved while maintaining a simple, unified structure that is easy to manufacture and handle. This merging approach eliminates the need for separate drives while still enabling independent speed control.

Inventive Principle:
Principle #5Merging (Combining)

3Speed

If the pin and shoulder rotate in opposite directions at different speeds, then different speeds can be achieved, but wear on the contact surface between pin and shoulder increases

Engineering Contradiction:
Improvedifferent rotational speedsVSAvoidcontact surface wear
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

Instead of rotating the pin and shoulder in opposite directions, both components rotate in the same rotational direction. This inversion of the conventional approach reduces the relative speed between the pin and shoulder contact surfaces, thereby minimizing wear and improving the reliability and lifespan of the friction stir welding tool while still maintaining different absolute rotation speeds.

Inventive Principle:
Principle #13The other way round (Inversion)

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 configuration results in a robust and simple construction that allows for different speeds between the pin and shoulder, reducing wear and enabling high-quality welds by maintaining equal rotation direction, thus improving the welding process and seam quality.

Implementation Method 1

a planetary gear with a ring gear, a planet carrier and a sun gear is provided, which planetary gear is connected to the drive shaft, pin and shoulder

Methodology Applied
Scientific EffectPlanetary gear mechanism: Epicyclic Gearing

Implementation Method 2

adjacent components are joined by mixing material in a joining zone around the friction stir welding tool

Methodology Applied
Scientific EffectFriction stir welding: Friction Welding

Data Source

PatentEP4284588B1Friction stir welding tool and friction stir welding method
Publication Date: 2025.01.29 STIRTEC GMBH
  • EP4284588B1 patent drawingFigure 1

AI summary

The invention relates to a friction stir welding tool for a machine tool which has a frame (6) and a spindle (5) that can be rotated relative to the frame (6). The friction stir welding tool has a pin (1), a shoulder (2), and a drive shaft (4) which can be connected to the spindle (5) of the machine tool in order to rotate the pin (1) and the shoulder (2) about a rotational axis (3) via the spindle (5), wherein the shoulder (2) can be rotated about the rotational axis (3) relative to the pin (1). The aim of the invention is to obtain different speeds of the pin (1) and the shoulder (2) in a particularly structurally simple and simultaneously robust manner. According to the invention, this is achieved by providing a planetary transmission (7) with a ring gear (11), a planet carrier (8), and a sun gear (9), said planetary transmission being connected to the drive shaft (4), the pin (1), and the shoulder (2). The pin (1) or the shoulder (2) is connected to the planet carrier (8) so that the pin (1) and the shoulder (2) can be rotated about the rotational axis (3) at different rotational speeds but in the same rotational direction by driving the drive shaft (4) by means of the spindle (5).