Recessed Joining Structure for Strong Small-Hole Welds

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Solution Overview

Problem

Existing joining structures face insufficient joining strength due to a small welding area of the filler material, particularly when the hole diameter of the penetrating part is small.

Innovation Solution

A joining structure is developed where a first member with a recess formed by press molding is used, allowing a third member with a flange to be arc-welded towards the bottom of the recess via a penetrating part in a second member, increasing the welding area and securing the joining strength by solidification contraction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the hole diameter of the penetrating part is small, then the second member can be securely positioned, but the welding area of the filler material becomes small resulting in insufficient joining strength

Engineering Contradiction:

Improvejoining strengthVSAvoidwelding area

Core Design Contradiction:

StrengthVSArea of stationary object

Solution Approach 1:

The first member is provided with a recess formed by press molding that extends in the thickness direction. This recess allows the filler material to be welded not only on the surface but also on the inner wall surfaces and bottom of the recess, effectively increasing the welding area from a two-dimensional surface to a three-dimensional volume, thereby resolving the contradiction between small hole diameter and sufficient welding area

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The recess is formed within the first member, creating a nested structure where the penetrating part of the second member is positioned within the recess of the first member. This nesting allows the filler material to utilize the recess space for welding, increasing the effective welding area without requiring a larger hole diameter in the second member

Inventive Principle:

Principle #7Nested doll (Nesting)

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 increased welding area of the filler material enhances the joining strength between the first, second, and third members, improving mechanical stability even with thin first member plates.

Implementation Method 1

The second member is compressed by the flange and the first member by solidification contraction of the third member, and the second member is therefore fixed between the flange of the third member and the first member

Methodology Applied

Scientific EffectSolidification contraction: Phase Change

Implementation Method 2

The third member includes a flange that presses a peripheral edge of the penetrating part, and is arc-welded toward at least a bottom of the recess via the penetrating part

Methodology Applied

Scientific EffectArc heating: Electric Arc

Data Source

PatentUS11839940B2Joining structure

Publication Date: 2023.12.12 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

Second member 20 includes a material that is difficult to weld to first member 10. In first member 10, recess 11 is formed by press molding such that a lower surface of first member 10 opposite to second member 20 protrudes. Third member 30 is arc-welded toward at least a bottom of recess 11 via penetrating part 21 of second member 20. Second member 20 is compressed by flange 31 and first member 10 by solidification contraction of third member 30, and second member 20 is therefore fixed between flange 31 of third member 30 and first member 10.