Cylindrical Battery Welding Rod Overlap Measurement for Stable Joining

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Solution Overview

Problem

Existing cylindrical battery welding apparatuses lack a means to accurately measure the degree of overlap between welding rods, which is crucial for ensuring consistent welding quality due to variations in battery shape, tab position, and rod length during the welding process.

Innovation Solution

A welding apparatus with an upper and lower welding unit, equipped with a displacement measurement unit to measure the displacement of a buffer portion between the welding rods, allowing precise adjustment of the degree of overlap and ensuring tight contact during resistance welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If resistance welding is performed without measuring the overlap between welding rods, then the welding process is simple and fast, but the welding quality becomes inconsistent due to variations in battery shape, tab position, and rod length

Engineering Contradiction:
Improvewelding quality consistencyVSAvoidwelding apparatus structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical measurement systems with a laser displacement sensor that uses optical fields to measure the overlap between welding rods. The laser sensor emits laser beams and detects the position of the welding rod ends through optical reflection, converting physical overlap measurement into optical signal processing. This substitution achieves high-precision measurement (reducing welding quality variation) while keeping the apparatus relatively simple, as the laser sensor integrates easily into the existing welding device without requiring complex mechanical linkages or contact-based measurement mechanisms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the welding apparatus includes measurement and adjustment mechanisms for welding rod overlap, then welding quality consistency improves, but the apparatus complexity and cost increase

Engineering Contradiction:
Improvewelding process reliabilityVSAvoidwelding apparatus structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback control system where the laser displacement sensor continuously measures the overlap between upper and lower welding rods, and the control unit adjusts the welding rod positions based on these measurements to maintain optimal overlap. The sensor provides real-time feedback on welding rod positioning, and the control system automatically compensates for variations in battery shape, tab position, and rod length. This feedback mechanism ensures consistent welding quality (improving reliability) while using a relatively simple apparatus structure, as the feedback loop integrates standard sensor and control components into the existing welding apparatus.

Inventive Principle:
Principle #23Feedback

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 consistent-quality welding results by accurately measuring and adjusting the overlap between welding rods, addressing the variability in battery shape and tab position, thereby improving the reliability of the welding process.

Implementation Method 1

a laser displacement sensor (500)

Methodology Applied
Scientific EffectLaser measurement: Laser

Implementation Method 2

resistance welding

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4678324A1Welding apparatus for cylindrical battery having welding rod overlap measuring unit
Publication Date: 2026.01.14 LG ENERGY SOLUTION LTD
  • EP4678324A1 patent drawingFigure 1
  • EP4678324A1 patent drawingFigure 2
  • EP4678324A1 patent drawingFigure 3

AI summary

Disclosed is a welding apparatus including an upper welding unit including an upper welding rod, a first object to be joined located under the upper welding rod, a second object to be joined located under the first object to be joined, and a lower welding unit including a lower welding rod located under the second object to be joined, wherein the first object to be joined and the second object to be joined are welded to each other by resistance welding using the upper welding rod and the lower welding rod, and a displacement measurement unit configured to measure the displacement of a buffer portion provided on at least one of an upper end of the upper welding rod or a lower end of the lower welding rod by further pressing in the state in which the upper welding rod, the first object to be joined, the second object to be joined, and the lower welding rod face each other in tight contact with each other.