Aluminum Bumper Beam Local Softening for Energy Absorption

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Solution Overview

Problem

The existing methods for manufacturing bumper beams from heat-treatable aluminum alloy extrusions require multiple costly heat treatments, such as reversion treatment, age hardening, and annealing, which reduce productivity and increase costs, and result in decreased formability and collision energy absorption characteristics.

Innovation Solution

A bumper structure with a heat-treatable aluminum alloy extrusion subjected to plastic working, where the longitudinal portion is pre-treated with reversion treatment to form a heat-affected zone in the bumper stay joint sections, followed by age hardening to create a low-hardness region, reducing hardness and increasing formability and collision energy absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple heat treatments (reversion treatment, age hardening, and annealing) are applied to improve formability and collision energy absorption, then the formability and energy absorption characteristics are improved, but productivity decreases and manufacturing costs increase

Engineering Contradiction:

Improvecollision energy absorption characteristicsVSAvoidproductivity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent extracts and eliminates the annealing step from the traditional three-step heat treatment process. By using reversion treatment followed directly by age hardening, the patent achieves the same softening effect without requiring the separate annealing operation, thereby improving productivity while maintaining collision energy absorption characteristics.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the softening function into the reversion treatment step, which simultaneously achieves both softening and prepares the material for age hardening. This consolidation of functions reduces the total number of heat treatment steps from three to two, improving manufacturing efficiency.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

Engineering Contradiction:

Improvecollision energy absorption characteristicsVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes the annealing step from the heat treatment sequence, eliminating the associated equipment usage, energy consumption, and time costs. This reduction in process steps directly lowers manufacturing costs while maintaining the required collision energy absorption performance through the optimized reversion treatment and age hardening combination.

Inventive Principle:

Principle #2Taking out (Extraction)

3Strength

If the whole bumper beam is subjected to age hardening after plastic working, then strength is improved, but the hardness of joint sections increases reducing formability

Engineering Contradiction:

ImprovestrengthVSAvoidformability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent applies reversion treatment to the joint sections before plastic working to pre-soften these specific areas. This preliminary softening action ensures that the joint sections remain formable during subsequent plastic working operations, while the rest of the bumper beam maintains its strength through age hardening.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates local quality differences by applying reversion treatment specifically to joint sections rather than the entire bumper beam. This localized heat treatment creates a gradient of material properties where joint sections have lower hardness for better formability, while other regions maintain higher strength after age hardening.

Inventive Principle:

Principle #3Local quality

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 efficiently produces a cost-effective bumper beam with improved collision energy absorption characteristics by forming a low-hardness region in the bumper stay joint sections, enhancing the beam's ability to absorb collision energy while maintaining structural integrity.

Implementation Method 1

The term 'heat-affected zone', as used herein, refers to a portion that was heated through heat conduction from a portion heated for reversion treatment

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

The whole bumper beam is subjected to age hardening after the plastic working. The portion of the bumper beam subjected to plastic working is subjected to reversion treatment before the plastic working

Methodology Applied

Scientific EffectAge hardening: Heat Treatment

Data Source

PatentUS9371047B2Bumper structure and method for manufacturing bumper beam

Publication Date: 2016.06.21 KOBE STEEL LTD

AI summary

There is provided a bumper beam that is formed of a 7000 series aluminum alloy hollow extrusion, has a crushed longitudinal portion, and locally has a low-hardness region in a bumper stay joint section. A portion (portion to be heated) of end portions of the bumper beam formed of a tempered member of a heat-treatable aluminum alloy extrusion is subjected to reversion treatment, thereby forming a heat-affected zone in a bumper stay joint section. An end region (portion to be crushed) of the heated portion is subjected to cold crushing, and then the whole bumper beam is subjected to age hardening. The heated portion and a non-heat-affected zone are hardened through the age hardening, thereby forming a low-hardness region that overlaps the joint section in a portion of the heat-affected zone.