Wireless Temperature Sensing in Electric Spindles for FSW

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Solution Overview

Problem

Existing friction stir welding (FSW) processes face challenges with temperature measurement imprecision due to indirect temperature sensing in rotating tools, leading to inconsistent weld quality and tool imbalance issues, particularly in high-speed applications.

Innovation Solution

An electrospindle design with wireless signal transmission between a rotating part and housing, integrated thermocouples, and compact connectors for direct temperature measurement, ensuring precise temperature control and balance without additional components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If indirect temperature sensing is used in rotating tools, then the device complexity is reduced, but the measurement precision deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidmeasurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces indirect mechanical temperature sensing with direct integrated thermocouple measurement. The thermocouple is embedded in the rotating part to provide direct temperature measurement at the tool interface, eliminating the need for indirect sensing methods and achieving both direct measurement and acceptable device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a wireless transmission system as an intermediary to transfer temperature data from the rotating part to the stationary housing. This mediator enables direct temperature measurement while maintaining device simplicity by eliminating physical cable connections and associated complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If additional components are added for temperature measurement, then the measurement precision is improved, but the device complexity increases

Engineering Contradiction:

Improvemeasurement precisionVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the temperature measurement function directly into the rotating part by integrating the thermocouple. This combination achieves precise temperature measurement without adding separate external components, as the thermocouple becomes an intrinsic part of the rotating assembly rather than an add-on component.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The rotating part serves multiple functions: it provides mechanical rotation for welding and simultaneously houses the thermocouple for temperature measurement. This multi-functionality eliminates the need for dedicated separate measurement components, reducing overall device complexity while maintaining measurement precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If wireless signal transmission is implemented, then the measurement precision is improved through direct sensing, but the device complexity increases

Engineering Contradiction:

Improvemeasurement precisionVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces physical cable connections with wireless signal transmission. This substitution eliminates the mechanical complexity of cable management, connectors, and associated components while enabling direct temperature sensing in the rotating part, thereby improving measurement precision without proportionally increasing device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If compact connectors are used, then the device complexity is reduced, but the measurement precision may deteriorate

Engineering Contradiction:

Improvedevice complexityVSAvoidmeasurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent extracts the connector function entirely from the system by implementing wireless signal transmission. This extraction eliminates the need for physical connectors altogether, reducing device complexity while maintaining measurement precision through the wireless transfer of temperature data from the integrated thermocouple.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Achieves precise temperature control and tool balance, enhancing weld quality and performance in FSW and machining operations with reduced complexity and maintenance needs.

Implementation Method 1

The tool holder comprises a thermocouple connected to the connector

Methodology Applied

Scientific EffectThermocouple: Thermocouple

Implementation Method 2

means for wireless transmission between the rotating part and the housing of the signal coming from the connector

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4327059B1Electric spindle provided with a temperature measuring device, and machine comprising such electric spindle

Publication Date: 2026.01.14 INSTITUT MAUPERTUIS

Figure 1~2
Figure 3~4
Figure 5

AI summary

The invention relates to an electric spindle (2) which comprises a housing (4), a rotating part (6) mounted so as to rotate with respect to the housing (4), the rotating part having a recess (14) for receiving a tool holder, the rotating part comprising at least one connector (26) arranged on an external face (24) of the rotating part and configured to receive a signal, and means for wirelessly transmitting the signal from the connector (26) between the rotating part (6) and the housing (4).