Laser Welding Tack Nugget Overlap to Suppress Plate Deformation

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Solution Overview

Problem

During laser welding, deformation of the object to be welded occurs due to heat distortion and residual stress, and the tack welded parts are prone to peeling off after main welding, leading to abnormal noise and loss of strength.

Innovation Solution

A welding method where tack weld nuggets are formed along a virtual closed curve on the object to be welded, and main weld nuggets are overlapped on these tack weld nuggets to suppress deformation and prevent peeling, with the main weld nuggets encasing the tack weld nuggets to ensure no remaining tack weld parts after completion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If tack welding is performed before main welding to suppress deformation, then deformation suppression is improved, but the tack welded part peels off after main welding causing noise

Engineering Contradiction:
Improvedeformation suppressionVSAvoidtack welded part retention
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent merges the tack welding process with the main welding process by positioning main weld nuggets to overlap with tack weld nuggets. This integration ensures that the weaker tack welded parts are reinforced or replaced by stronger main welds, preventing peeling while maintaining deformation suppression benefits throughout the welding sequence.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent applies preliminary tack welding at specific positions along a closed curve before performing main welding. This preliminary action establishes initial structural stability to suppress deformation during the subsequent main welding process, while the main welds are strategically positioned to eliminate remaining tack welded parts.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If main weld nuggets overlap tack weld nuggets, then peeling is prevented, but deformation suppression effect is lost

Engineering Contradiction:
Improvepeeling preventionVSAvoiddeformation suppression
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent segments the welding process into distinct tack welding and main welding stages, with tack welds performed at multiple positions along a closed curve before main welding. This segmentation allows the structure to gain incremental stability at each tack weld position, maintaining deformation suppression throughout the sequence while enabling complete overlap with main welds.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary tack welding at multiple positions before main welding to establish progressive structural stability. Each tack weld provides temporary reinforcement that suppresses deformation during subsequent operations, and the main welds are then applied to overlap and reinforce these preliminary tack welds.

Inventive Principle:
Principle #10Preliminary action

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 method effectively suppresses deformation during main welding and prevents peeling of tack welded parts after main welding, maintaining structural integrity and eliminating abnormal noise.

Implementation Method 1

a welding method for irradiating an object to be welded including a plurality of metallic plates that are stacked on each other with a high energy beam and performing welding

Methodology Applied
Scientific EffectLaser beam welding: Laser Beam Welding

Data Source

PatentUS9962789B2Welding method
Publication Date: 2018.05.08 TOYOTA JIDOSHA KK

AI summary

A welding method according to the present invention is a welding method for irradiating an object to be welded including a plurality of metallic plates that are stacked on each other with a high energy beam and performing welding. The welding method includes: forming a plurality of tack weld nuggets along a virtual closed curve on a part to be welded of the object to be welded; and forming a plurality of main weld nuggets so that the main weld nuggets overlap the plurality of respective tack weld nuggets.