Wavy Butt Weld Boundary for Higher-Strength Metal Plate Joints

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Solution Overview

Problem

Existing butt welding techniques often result in insufficient joining strength between metal plates due to a straight welding boundary line, leading to potential fractures and poor welding when the area of the joint is inadequate, and increasing the number of butt portions is limited by design constraints.

Innovation Solution

The use of a wavy or curved welding boundary line that extends beyond a straight line connecting the ends of the weld, increasing the joint area and preventing displacement of non-welded portions during thermal expansion, thereby enhancing joining strength without increasing the number of butt portions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a straight welding boundary line is used in butt welding, then the welding process is simple, but the joining strength is insufficient and the joint area is inadequate

Engineering Contradiction:
Improvewelding process simplicityVSAvoidjoining strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The welding boundary line is designed as a curved or wavy line instead of a straight line. This curvature increases the length of the welding boundary, thereby increasing the joint area and improving joining strength while maintaining manufacturing simplicity through standardized curved boundary designs

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Strength

If the number of butt portions is increased to improve joining strength, then the joining strength increases, but the design complexity increases and design limitations are reached

Engineering Contradiction:
Improvejoining strengthVSAvoidnumber of butt portions
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

Instead of increasing the number of butt portions (one-dimensional solution), the invention extends the welding boundary line in the two-dimensional plane to increase joint area. This dimensional approach allows achieving higher joining strength without adding more connection points or increasing structural complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Area of stationary object

If the joint area is increased by adding more butt portions, then the joining strength improves, but the manufacturing complexity and design constraints increase

Engineering Contradiction:
Improvejoint areaVSAvoidnumber of butt portions
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The welding boundary line is designed as a curved or wavy line instead of a straight line. This curvature increases the length of the welding boundary, thereby increasing the joint area and improving joining strength while maintaining manufacturing simplicity through standardized curved boundary designs

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 approach significantly improves the joining strength between metal plates by increasing the joint area and reducing the likelihood of poor welding, while also allowing for varying plate thicknesses and easier removal from bending dies without interference.

Implementation Method 1

displacement in non-welded portions due to thermal expansion

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3417983B1Metal member and method of manufacturing the same
Publication Date: 2021.08.04 TOYOTA JIDOSHA KK
  • EP3417983B1 patent drawingFigure 1
  • EP3417983B1 patent drawingFigure 2
  • EP3417983B1 patent drawingFigure 3

AI summary

A metal member (1, 11) includes a first plate (2, 12), and a second plate (3, 13) abutting against and welded to the first plate (2, 12) in at least one butt portion (SI, S2, S3). In the butt portion (S1, S2, S3), a length from a first end (P1, P11, P13) to a second end (P2, P12, P14) of a welding boundary line (L1, L11, L13) between the first plate (2, 12) and the second plate (3, 13) is longer than a length of a straight line (L2, L14) connecting the first end (P1, P11, P13) to the second end (P2, P12, P14) of the welding boundary line (L1, L11, L13).