Friction-Current Joining for Uniform Heating and Joint Quality

Solution Overview

Problem

Conventional friction welding techniques face issues with fiber deflections, hardening, and uneven heating, leading to reduced reproducibility and quality in joining processes, particularly when dealing with materials with different melting behaviors.

Innovation Solution

A method and apparatus for joining workpieces using friction and current, which eliminates the high torque peaks and frictional relative movement by employing conductive electrical heating, allowing for uniform heating and reduced mechanical stress, and omitting the friction phase, thereby improving reproducibility and joint quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional friction welding with friction phase is used, then joining is achieved, but fiber deflections and hardening occur leading to reduced quality

Engineering Contradiction:

Improvejoint qualityVSAvoidfiber deflections and hardening

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention extracts and removes the harmful friction phase from the conventional friction welding process. By separating the heating function (achieved through electrical heating) from the friction phase, the process eliminates fiber deflections and hardening while maintaining the joining capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical friction-based heating system with an electrical heating system. Instead of relying on mechanical friction to generate heat and plasticize the material, electrical heating elements directly heat the workpieces, eliminating the harmful mechanical friction phase.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If friction phase with high contact pressure is used, then plasticization is achieved, but high torque peaks occur producing high mechanical stress

Engineering Contradiction:

Improveplasticization temperatureVSAvoidtorque peaks and mechanical stress

Core Design Contradiction:

TemperatureVSForce

Solution Approach 1:

The invention replaces the mechanical friction-based heating system with an electrical heating system. Instead of relying on mechanical friction to generate heat and plasticize the material, electrical heating elements directly heat the workpieces, eliminating the harmful mechanical friction phase.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the fundamental parameter for achieving plasticization from mechanical friction (torque-based) to electrical heating (temperature-based). This parameter change allows plasticization to occur without the high torque peaks and mechanical stress associated with conventional friction welding.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conventional friction welding is used, then joining is achieved, but reproducibility is reduced due to uneven heating

Engineering Contradiction:

ImprovereproducibilityVSAvoidheating uniformity

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The invention replaces the mechanical friction-based heating system with an electrical heating system. Instead of relying on mechanical friction to generate heat and plasticize the material, electrical heating elements directly heat the workpieces, eliminating the harmful mechanical friction phase.

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

The method achieves higher reproducibility and quality in joining, reduces workpiece shortening, and allows for precise dimensional control, with lower forces and torques required, while preventing hardening and fiber imperfections, resulting in improved fatigue strength and corrosion resistance.

Implementation Method 1

the electric current flowing through the contacted workpieces conductively heats the same

Methodology Applied

Scientific EffectConductive electrical heating: Conduction (thermal)

Implementation Method 2

the electric current flowing through the contacted workpieces conductively heats the same

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 3

the contacting joining surfaces are ground and made smooth by mutual relative movement... with frictional relative movement under high contact pressure and deep plasticization of the workpieces due to the resulting frictional heat

Methodology Applied

Scientific EffectFrictional heat: Friction

Data Source

PatentUS12103102B2Method and apparatus for friction current joining

Publication Date: 2024.10.01 KUKA DEUT GMBH

AI summary

A method and apparatus for joining using friction and current, wherein the friction/current joining apparatus includes a friction device, a forging device, an electrical current source, and a programmable controller, as well as workpiece holders for the workpieces to be joined. The friction/current joining apparatus is controlled such that, in a contacting phase, the workpieces are initially moved along a process axis, and their mutually facing joining surfaces oriented transverse to a common process axis are brought into contact. In a grinding phase, while subjected to contact pressure by mutual relative movement, the joining surfaces, are ground together and made smooth. At the end of the grinding phase, the relative frictional movement is permanently stopped and, in a forging phase following the grinding phase, the workpieces are pressed together, plasticized, and joined while subjected to contact pressure on their contacting joining surfaces along the process axis, and subjected to conductive heating with electrical current.