Socket Contact Groove Structure for Uniform Pull-Off Force

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Solution Overview

Problem

Existing socket contacts made from flat spring steel or solid materials face issues with insufficient current carrying capacity and inconsistent pull-off forces due to brittleness and uneven bending during manufacturing, leading to unreliable electrical connections.

Innovation Solution

A socket contact with a hollow cylindrical connection area that accommodates a stripped electrical conductor, featuring a crimped connection and a radially inward-folded contact tongue with a circumferential groove to prevent brittleness and ensure uniform pull-off forces, achieved through machining and crimping processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a socket contact is made from flat spring steel sheet using stamping and bending technique, then it is easy to manufacture, but the current-carrying capacity is not sufficient

Engineering Contradiction:
Improveease of manufactureVSAvoidcurrent-carrying capacity
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The socket contact combines copper or copper alloy (for electrical conductivity) with steel (for mechanical strength and spring properties) in a composite structure. The hollow cylindrical body provides current-carrying capacity while the spring steel sheet folded into contact tongues provides mechanical strength and contact pressure, achieving both ease of manufacture and sufficient current-carrying capacity

Inventive Principle:
Principle #40Composite materials

2Device complexity

If the contact tongue is folded radially inward without a groove, then the structure is simpler, but the contact tongue becomes brittle at the base due to the bending process

Engineering Contradiction:
Improvestructural simplicityVSAvoidbrittleness resistance
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

A groove is introduced at the base of the contact tongue where the bending stress is highest. This local modification changes the stress distribution and prevents crack initiation, specifically addressing the brittleness problem at the critical location without complicating the overall structure

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If the contact tongue is folded radially inward without a groove, then manufacturing is simpler, but the pull-off forces fluctuate and are set to the upper tolerance limit, leading to high overall pull-off forces

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidpull-off force uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The groove at the contact tongue base creates a consistent stress distribution point that ensures uniform bending behavior. This local feature controls the deformation pattern, resulting in consistent pull-off forces across all manufactured contacts and reducing variability to within tolerance limits

Inventive Principle:
Principle #3Local quality

4Reliability

If a solid material is used for the socket contact, then better electrical properties are achieved, but the contact tongue becomes brittle at the base due to the bending process

Engineering Contradiction:
Improveelectrical propertiesVSAvoidbrittleness resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The hollow cylindrical body is made of copper or copper alloy for optimal electrical properties, while the contact tongues are made from spring steel sheet folded into shape. This composite construction separates the electrical function (copper body) from the mechanical function (steel contact tongues), achieving both good electrical properties and resistance to brittleness

Inventive Principle:
Principle #40Composite materials

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 solution provides a reliable, cost-effective, and uniform electrical connection with reduced risk of breakage and consistent pull-off forces, enhancing product quality and manufacturing efficiency.

Implementation Method 1

At least one contact tongue (4) is machined from the cylindrical wall in a preferably machining step, which is folded radially inward

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The connection area is then crimped with a crimping tool, creating a reliable electrically conductive connection between the conductor and the socket contact

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP4078733B1Socket contact
Publication Date: 2024.10.16 HARTING ELECTRIC STIFTUNG & CO KG
  • EP4078733B1 patent drawingFigure 1~2

AI summary

The invention relates to a socket contact (1), which has a hollow cylindrical contact wire region (AB) for receiving a stripped end portion of an electrical conductor to be connected, and a hollow cylindrical contact region (KB) with a pin insertion opening (2) for receiving a contact pin, wherein the contact region (KB) has a cylinder wall with at least one radially inwardly folded contact blade (4), the free end of which points towards the pin insertion opening (2), and wherein the cylinder wall has an at least partially circumferential groove (5) for the contact blade in the region of the fold.