Thermoplastic Spring Sleeve Induction Welding

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing spring sleeves and spring pins have inconsistent spring characteristics due to deformation during assembly, leading to varying protrusion distances and altered spring properties, which is undesirable for applications requiring consistent performance.

Innovation Solution

The use of thermoplastic materials for the sleeve or pin, connected to a metal coil spring via induction welding, ensures consistent spring characteristics and protrusion lengths by avoiding deformation during assembly, with the induction welding process using high-frequency magnetic fields to secure the spring without stressing the helical spring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the helical spring is deformed during assembly by embossing or clamping, then the spring is fixed within the sleeve or on the pin, but the spring characteristics change and protrusion distances become inconsistent

Engineering Contradiction:

Improvespring characteristics consistencyVSAvoidassembly process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

A plastic component serves as an intermediary between the helical spring and the final assembly structure. The plastic is heated by induction to become moldable, allowing the spring to be inserted without deformation, then cools to lock the spring in place, thus fixing the spring without mechanical deformation that would alter its characteristics

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The plastic component's physical state is changed through induction heating, transitioning from solid to moldable state and back. This parameter change allows the spring to be inserted without force or deformation during the moldable phase, then locked in place when the plastic solidifies, maintaining spring characteristics consistency

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the helical spring is inserted into a metal sleeve and deformed for fixation, then the spring is held within the sleeve, but the protrusion distance varies and spring characteristics are altered

Engineering Contradiction:

Improveprotrusion distance consistencyVSAvoidassembly structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The plastic component acts as a mediator that enables precise positioning of the helical spring. By becoming moldable through induction heating, it allows the spring to be inserted to an exact position without deformation, then solidifies to maintain that precise position, ensuring consistent protrusion distance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The plastic component is prepared in advance by heating it to a moldable state before spring insertion. This preliminary action allows the spring to be positioned precisely without subsequent adjustments or deformations, ensuring manufacturing precision

Inventive Principle:

Principle #10Preliminary action

3Reliability

If induction welding is used to connect the plastic sleeve or pin to the metal spring, then consistent spring characteristics are maintained, but the manufacturing process requires induction heating equipment

Engineering Contradiction:

Improvespring characteristics consistencyVSAvoidmanufacturing equipment

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The traditional mechanical connection methods (embossing, clamping, screwing) are replaced with induction welding. This substitutes mechanical deformation and assembly with a thermal process that melts and bonds the plastic to the metal spring, maintaining spring characteristics while achieving reliable fixation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method allows for the production of spring sleeves and pins with consistent spring characteristics and lengths, ensuring reliable performance and easy, quick manufacturing, suitable for various applications including electrical switches, with the added benefit of insulating properties from the plastic material.

Implementation Method 1

the induction welding process using high-frequency magnetic fields to secure the spring without stressing the helical spring

Methodology Applied

Scientific EffectInduction heating: Induction Heating

Implementation Method 2

the induction welding process using high-frequency magnetic fields to secure the spring

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

connected to a metal coil spring via induction welding

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 4

The use of thermoplastic materials for the sleeve or pin, connected to a metal coil spring via induction welding

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentEP2823196B1Spring sleeve and spring pin

Publication Date: 2018.01.10 FEDERNFAB DIETZ

Figure 1a~1d
Figure 2a~2d
Figure 3a~3b

AI summary

The present invention relates to a spring sleeve (10) or a spring pin, consisting of a helical spring (12) made of metal, and at least one sleeve (14) fit on an end of the helical spring (12), said sleeve having a closed head (24), wherein the helical spring (12) protrudes from the sleeve (14), or at least one pin inserted at one end of the helical spring (12) with a head, wherein the head of the pin protrudes over the helical spring (12). The sleeve (14) or the pin consists of a thermoplastic plastic and the sleeve (14) or the pin is connected to the helical spring (12) by means of induction welding.