Lead-Free Brass Contact Plug Forming for Crack-Free Crimping

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Solution Overview

Problem

Lead-free brass alloys face challenges in achieving a balance between good cutting machinability and crimpability without crack formation, leading to high manufacturing costs and material loss due to their brittle-hard behavior and low ductility.

Innovation Solution

A process involving semihot forming of a crimping region in a lead-free brass alloy blank at a temperature between 250°C to 450°C, followed by cold forming of a plugging region to create lamellae, which provides low work hardening for ductile crimping and work hardening for elastic spring forces, reducing crack formation and material loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If lead-free brass alloy is used to maintain health safety, then harmful factors are reduced, but cutting machinability deteriorates due to brittle-hard behavior

Engineering Contradiction:

Improveharmful effect of leadVSAvoidcutting machinability

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by heating the lead-free brass alloy to a specific temperature range (250-450°C) during forming. This temperature parameter change transforms the material properties, making the alloy more ductile and easier to form without cracks, while maintaining lead-free composition for health safety.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by differentiating the treatment of different regions of the contact plug. The crimping region is heated to improve ductility locally, while other regions maintain their original properties. This localized thermal treatment resolves the contradiction between overall material strength and local formability.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If lead-free brass alloy is used to eliminate lead, then harmful factors are reduced, but crimpability deteriorates due to low ductility leading to crack formation

Engineering Contradiction:

Improveharmful effect of leadVSAvoidcrimpability without crack formation

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the temperature parameter during the crimping process by heating the crimping region to 250-450°C. This parameter change increases the ductility of the lead-free brass alloy, enabling reliable crimp connections without crack formation while maintaining the lead-free composition.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary action by pre-heating the crimping region before performing the crimping operation. This preliminary thermal treatment prepares the material by increasing its ductility, ensuring that the subsequent crimping process can be performed without causing cracks.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If cutting machining is used to produce contact plugs, then manufacturing precision is achieved, but material loss increases due to up to 50% waste

Engineering Contradiction:

Improvecutting machining precisionVSAvoidmaterial loss

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent replaces the mechanical cutting machining process with a thermal-forming process. By heating the lead-free brass alloy to 250-450°C and forming it into the final shape, the process eliminates the need for cutting operations, thereby reducing material loss while maintaining manufacturing precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the processing parameters from room-temperature mechanical cutting to elevated-temperature (250-450°C) forming. This parameter change enables near-net-shape production, significantly reducing material waste while achieving the required manufacturing precision for contact plugs.

Inventive Principle:

Principle #35Parameter changes

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 process enables reliable, crack-free crimp connections with reduced material loss and manufacturing costs, achieving durable and efficient production of lead-free contact plugs.

Implementation Method 1

semihot forming a first section of the blank to form a crimping region, the crimping region having an opening for insertion of a conductor end and the first section of the blank being heated to a semihot forming temperature before and/or during the semihot forming

Methodology Applied

Scientific EffectSemihot forming: Heat Treatment

Implementation Method 2

semihot forming a first section of the blank to form a crimping region

Methodology Applied

Scientific EffectPlasticity: Plasticity

Implementation Method 3

cold forming a second section of the blank to form a plugging region, the plugging region having a plurality of lamellae

Methodology Applied

Scientific EffectCold forming: Cold-forming

Data Source

PatentUS11848510B2Method for producing a contact plug, and contact plug

Publication Date: 2023.12.19 PHOENIX CONTACT GMBH & CO KG

AI summary

A process for producing a contact plug includes: providing a blank made of a lead-free brass alloy; semihot forming a first section of the blank to form a crimping region, the crimping region having an opening for insertion of a conductor end and the first section of the blank being heated to a semihot forming temperature before and/or during the semihot forming; and cold forming a second section of the blank to form a plugging region, the plugging region having a plurality of lamellae.