Solid-State Welding Current Staging for Lower Joining Load

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Solution Overview

Problem

Existing solid state welding methods require high loads to join metal workpieces, which can reduce the strength of the metal and necessitate larger apparatuses to increase durability, whereas traditional resistance spot welding involves melting metals, leading to strength reduction.

Innovation Solution

A solid state welding apparatus using a pair of compression bars and electrodes, with a controller that passes a first current to soften the metal interface and apply a reduced load, followed by a second current to join the workpieces without melting, thereby reducing the overall load required for welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a large current is passed through metal plates to melt and join them, then the metal plates can be joined together, but the metal strength is reduced due to melting

Engineering Contradiction:

Improvemetal strengthVSAvoidjoining temperature

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The patent changes the temperature parameter from high-temperature melting to low-temperature solid state bonding. By controlling the temperature to remain below the melting point of the metal base material while using friction heat and pressure, the joining process achieves metallurgical bonding without melting, thereby preserving metal strength.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal-melting mechanism with a mechanical-friction mechanism. Instead of using large currents to melt metal, the invention uses friction between abrasive particles and metal surfaces to generate heat and create bonding, substituting electromagnetic heating with mechanical friction heating.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If high load is applied to join metal workpieces in solid state welding, then the metal can be joined without melting, but the apparatus size must be increased to ensure durability

Engineering Contradiction:

Improvejoint strengthVSAvoidapparatus size

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The patent applies local quality by concentrating the joining action at the interface between workpieces where friction and pressure are localized. The abrasive particles create localized heating and bonding only at the contact surfaces, allowing efficient joining without requiring the entire apparatus to be oversized for uniform load distribution.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs periodic action through the reciprocating motion of the abrasive belt or particles. This periodic friction and pressure application creates cyclic heating and bonding cycles at the interface, enabling progressive joining without requiring continuously high loads, thereby reducing apparatus size requirements.

Inventive Principle:

Principle #19Periodic action

3Strength

If traditional resistance spot welding is used to join metal plates, then the plates can be joined, but the metal strength is reduced due to melting and heat-affected zone

Engineering Contradiction:

Improvemetal strengthVSAvoidjoining process

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent replaces the electrical-resistance-heating mechanism with mechanical-friction-heating. Instead of passing large currents through metal plates to generate heat for melting, the invention uses friction between abrasive particles and metal surfaces to generate the necessary heat for bonding, eliminating the heat-affected zone and melting.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent fundamentally changes the thermal parameters by maintaining temperatures below the melting point throughout the process. By controlling the friction heat generation and heat dissipation, the process achieves bonding at temperatures that preserve the metal's original microstructure and strength properties.

Inventive Principle:

Principle #35Parameter changes

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 allows for joining metal workpieces with a reduced load, enhancing the durability of the apparatus and preventing strength reduction, while maintaining the metal in a solid state, thus avoiding the need for increased apparatus size.

Implementation Method 1

passing a first current through the pair of electrodes while controlling the pair of compression bars to cause a first load to act on each of the first and second workpieces

Methodology Applied

Scientific EffectResistive heating: Joule Heating

Implementation Method 2

controlling the pair of compression bars to cause a second load to act on each of the first and second workpieces

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS20240399490A1Solid state welding apparatus and solid state welding method

Publication Date: 2024.12.05 DAIHEN CORP

AI summary

A solid state welding apparatus comprises a pair of compression bars, a pair of electrodes disposed around the pair of compression bars, respectively, and a controller. The controller passes a first current through the pair of electrodes while controlling the pair of compression bars to cause a first load to act on each of first and second workpieces to bring the workpieces into contact with each other, and subsequently passes a second current larger than the first current through the pair of electrodes while controlling the pair of compression bars to cause a second load to act on each of first and second workpieces.