Friction Welding Element for Pressure-Tight Housing Connection

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Solution Overview

Problem

Existing methods for securing a female connector, such as a threaded insert, in a housing, particularly in applications like cooling water or hydraulic circuits, face challenges with pressure-tight sealing due to material compatibility issues, temperature stress, and mechanical damage, leading to compromised sealing effectiveness over time.

Innovation Solution

A friction-welding element with a connecting sleeve and a radially formed friction-welding jacket, featuring a conically shaped step and circumferential collar, is used to create a pressure-tight and non-rotatable connection by generating material-melting heat through friction, ensuring a reliable and durable bond between the connector and the housing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealing O-ring is used to ensure pressure-tight connection, then sealing effectiveness is improved, but the O-ring material must be compromised between resistance to aggressive media and temperature resistance

Engineering Contradiction:
Improvesealing effectivenessVSAvoidmaterial compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention removes the O-ring sealing element from the connection system entirely. Instead of relying on a separate sealing ring that requires material compromise, the friction-welding element creates a direct material-to-material seal between the housing and connecting sleeve through friction welding, eliminating the need for an O-ring and its associated material compatibility issues.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The sealing function is merged with the structural connection function. The friction-welding element serves both as the mechanical connector and the sealing element simultaneously, creating an integrated solution where the same joint that provides mechanical strength also provides pressure-tight sealing without requiring separate sealing components.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If the connecting socket is overmoulded during housing manufacture, then secure positioning is achieved, but the housing construction becomes complex requiring core pins and special mold design

Engineering Contradiction:
Improveconnection securityVSAvoidhousing mold construction
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The friction-welding element is designed with pre-formed friction welding contours and collar structures that enable direct friction welding attachment to the housing. This preliminary preparation of the connection interface eliminates the need for complex overmolding processes, core pins, and special mold designs while achieving secure mechanical and pressure-tight connection.

Inventive Principle:
Principle #10Preliminary action

3Productivity

If inductive heating and embedding is used to install the connection socket, then fast installation is achieved, but the connection may not provide sufficient pressure-tight sealing

Engineering Contradiction:
Improveinstallation speedVSAvoidpressure-tight connection
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention replaces inductive heating with friction welding, which uses mechanical friction generated by relative rotation between the friction-welding element and housing to create material-melting heat. This mechanical approach to heat generation achieves both fast installation and reliable pressure-tight sealing through the formation of a material bond that integrates the connecting sleeve with the housing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If a separate sealing ring is pressed into the housing wall, then sealing is achieved, but the sealing ring may be damaged by mechanical loads during installation

Engineering Contradiction:
Improvesealing functionVSAvoidsealing ring integrity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention eliminates the separate sealing ring component entirely, removing it from the installation process. The friction-welding element creates sealing through direct material-to-material bonding without requiring a separate sealing element that could be damaged during pressing or installation operations.

Inventive Principle:
Principle #2Taking out (Extraction)

5Reliability

If the O-ring is used for sealing, then initial sealing is achieved, but the O-ring ages and becomes brittle during operation, compromising long-term tightness

Engineering Contradiction:
Improveinitial sealingVSAvoidsealing durability
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention replaces the aging O-ring with a friction-welded connection that creates a permanent, non-degrading seal. The material-to-material bond formed through friction welding does not suffer from the aging and embrittlement that affects elastomeric sealing rings, providing long-term sealing durability without requiring replacement or maintenance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 solution provides a reliable, pressure-tight, and durable connection that withstands various media and temperature conditions, maintaining sealing integrity over time without the limitations of traditional sealing methods like O-rings.

Implementation Method 1

generating material-melting heat through friction

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

A friction-welding element with a connecting sleeve and a radially formed friction-welding jacket, featuring a conically shaped step and circumferential collar, is used to create a pressure-tight and non-rotatable connection by generating material-melting heat through friction

Methodology Applied
Scientific EffectFriction welding: Friction Welding

Data Source

PatentEP2956682B1Friction welding element, and a method for connecting the friction welding element to a housing
Publication Date: 2018.05.23 BOLLHOFF VERBINDUNGSTECHNIK GMBH
  • EP2956682B1 patent drawingFigure 1
  • EP2956682B1 patent drawingFigure 2
  • EP2956682B1 patent drawingFigure 3

AI summary

The invention relates to a friction welding method for attaching a connection socket (10), such as a threaded socket for example, in a housing (50). In order to improve the quality of the connection, the connection socket (10) is attached to the housing (50) using a friction welding element (1). The friction welding element (1) consists of the connection socket (10), on which a friction welding casing (30) with a radially outer friction welding contour (32) is molded. Connecting and sealing regions are produced between the friction welding element (1) and the housing (50) during the friction welding process by means of a special design of the friction welding contour (32).